CSSOM View Module

Abstract

The APIs introduced by this specification provide authors with a way to inspect and manipulate the visual view of a document. This includes getting the position of element layout boxes, obtaining the width of the viewport through script, and also scrolling an element.

Status of this Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

This is the 3 August 2012 Editor's Draft of CSSOM View. Please send comments to www-style@w3.org (archived) with [cssom-view] at the start of the subject line.

This document was produced by the CSS Working Group (part of the Style Activity).

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

Table of Contents

1. 1 Background
2. 2 Conformance
   1. 2.1 Web IDL
3. 3 Terminology
   1. 3.1 CSS pixels
4. 4 Extensions to the Window Interface
   1. 4.1 The MediaQueryList Interface
   2. 4.2 The Screen Interface
5. 5 Extensions to the Document Interface
   1. 5.1 The CaretPosition Interface
6. 6 Extensions to the Element Interface
   1. 6.1 The getClientRects() and getBoundingClientRect() methods
   2. 6.2 Element Scrolling Members
   3. 6.3 The clientTop, clientLeft, clientWidth, and clientHeight attributes
7. 7 Extensions to the HTMLElement Interface
8. 8 Extensions to the Range Interface
9. 9 Extensions to the MouseEvent Interface
10. 10 Rectangles
    1. 10.1 The ClientRectList Interface
    2. 10.2 The ClientRect Interface
11. References
    1. Normative references
12. Acknowledgments

1 Background

Many of the features defined in this specification have been supported by browsers for a long period of time. The goal of this specification is to define these features in such a way that they can be implemented by all browsers in an interoperable manner. The specification also defines a couple of new features that will hopefully be useful to authors. (If they are not you can bug us!)

2 Conformance

All diagrams, examples, and notes in this specification are non-normative, as are all sections explicitly marked non-normative. Everything else in this specification is normative.

The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this document are to be interpreted as described in RFC2119. For readability, these words do not appear in all uppercase letters in this specification. [RFC2119]

Requirements phrased in the imperative as part of algorithms (such as "strip any leading space characters" or "return false and terminate these steps") are to be interpreted with the meaning of the key word ("must", "should", "may", etc) used in introducing the algorithm.

Conformance requirements phrased as algorithms or specific steps may be implemented in any manner, so long as the end result is equivalent. (In particular, the algorithms defined in this specification are intended to be easy to follow, and not intended to be performant.)

User agents may impose implementation-specific limits on otherwise unconstrained inputs, e.g. to prevent denial of service attacks, to guard against running out of memory, or to work around platform-specific limitations.

When a method or an attribute is said to call another method or attribute, the user agent must invoke its internal API for that attribute or method so that e.g. the author can't change the behavior by overriding attributes or methods with custom properties or functions in ECMAScript.

Unless otherwise stated, string comparisons are done in a case-sensitive manner.

A conforming user agent implements all the requirements made by this specification.

2.1 Web IDL

The IDL fragments in this specification must be interpreted as required for conforming IDL fragments, as described in the Web IDL specification. [WEBIDL]

3 Terminology

Terminology used in this specification is from DOM Core, CSSOM and HTML. [DOM] [CSSOM] [HTML]

MouseEvent is defined in …

The HTML body element is the first body HTML element child of the root HTML element html.

Content edge, padding edge, border edge, and canvas are defined by CSS.

Viewport and initial containing block are defined by CSS 2.1 unless there is an ancestor foreignObject element in the http://www.w3.org/2000/svg namespace in which case that element acts as viewport and initial containing block.

The term content refers to the dimensions of the element's content area, including overflown content.

The term document content refers to the area on the canvas that is rendered upon, excluding content on negative axis.

3.1 CSS pixels

All coordinates and dimensions for the APIs defined in this specification are in CSS pixels.

This does not apply to e.g. matchMedia() as the units are explicitly given there.

4 Extensions to the Window Interface

partial interface Window {
    MediaQueryList matchMedia (DOMString query);
    readonly attribute Screen screen;
    readonly attribute long innerWidth;
    readonly attribute long innerHeight;
    readonly attribute long scrollX;
    readonly attribute long pageXOffset;
    readonly attribute long scrollY;
    readonly attribute long pageYOffset;
    void scroll (long x, long y);
    void scrollTo (long x, long y);
    void scrollBy (long x, long y);
    readonly attribute long screenX;
    readonly attribute long screenY;
    readonly attribute long outerWidth;
    readonly attribute long outerHeight;
};

screen of type Screen, readonly

The screen attribute must return the screen object associated with the Window object. It always returns the same object.

Accessing screen through a WindowProxy object might yield different results when the Document is navigated.

innerWidth of type long, readonly

The innerWidth attribute must return the viewport width including the size of a rendered scroll bar (if any).

The following snippet shows how to obtain the width of the viewport:

var viewportWidth = innerWidth

innerHeight of type long, readonly

The innerHeight attribute must return the viewport height including the size of a rendered scroll bar (if any).

scrollX of type long, readonly

The scrollX attribute attribute must return the x-coordinate, relative to the initial containing block origin, of the left of the viewport.

pageXOffset of type long, readonly

The pageXOffset attribute attribute must return the value returned by the scrollX attribute.

scrollY of type long, readonly

The scrollY attribute attribute must return the y-coordinate, relative to the initial containing block origin, of the top of the viewport.

pageYOffset of type long, readonly

The pageYOffset attribute attribute must return the value returned by the scrollY attribute.

screenX of type long, readonly

The screenX attribute must return the x-coordinate, relative to the origin of the screen of the output device, of the left of the client window as number of pixels, or zero if there is no such thing.

screenY of type long, readonly

The screenY attribute must return the y-coordinate, relative to the origin of the screen of the output device, of the top of the client window as number of pixels, or zero if there is no such thing.

outerWidth of type long, readonly

The outerWidth attribute must return the width of the client window. If there is no client window this attribute must return zero.

outerHeight of type long, readonly

The outerHeight attribute must return the height of the client window. If there is no client window this attribute must return zero.

matchMedia (DOMString), returns MediaQueryList

When the matchMedia operation is invoked these steps must be run:

1. Let parsed_media_query_list be the result of parsing media_query_list.

2. Return a new MediaQueryList object, associated with the Window object, with parsed_media_query_list as its associated media query list.

scroll (long, long), returns void

When the scroll operation is invoked these steps must be run:

1. If either x or y is infinite or NaN terminate this algorithm.

2. If document content can have overflow to the right

   Let x be max(0, min(x, content width - content edge width)).

   If document content can have overflow to the left (under right-to-left conditions)

   Let x be min(0, max(x, content edge width - content width)).

3. Let y be max(0, min(y, document content height - viewport height excluding the size of a rendered scroll bar (if any))).

4. Align the x-coordinate x of the document content with the left of the viewport and align the y-coordinate y of the document content with the top of the viewport.

5. If the aligning caused content to move queue a task to fire an event named scroll that bubbles at the Document object, unless a task to fire that event at the Document object was already queued.

scrollTo (long, long), returns void

When the scrollTo operation is invoked, the user agent must act as if the scroll() method was invoked with the same arguments.

scrollBy (long, long), returns void

When the scrollBy operation is invoked, the user agent must act as if the scroll() method was invoked with x plus scrollX as first argument and y plus scrollY as second argument.

4.1 The MediaQueryList Interface

A MediaQueryList interface has an associated media query list set on creation and an associated list of media query list listeners, which is initially empty.

If the associated media query list changes in evaluation then, for each listener in the list of media query list listeners — in appending order, queue a task that invokes the listener, passing as argument the MediaQueryList object.

function handleOrientationChange(mql) {    if(mql.matches) // landscape      …    else      …  }  var mql = matchMedia("(orientation:landscape)")  mql.addListener(handleOrientationChange)

interface MediaQueryList {
    readonly attribute DOMString media;
    readonly attribute boolean matches;
    void addListener (MediaQueryListListener listener);
    void removeListener (MediaQueryListListener listener);
};

media of type DOMString, readonly

The media attribute must return the serialized form of the associated media query list.

matches of type boolean, readonly

The matches attribute must return true if the associated media query list matches the state of the rendered Document and false if it does not.

addListener (MediaQueryListListener), returns void

When the addListener operation is invoked listener must be appended to the list of media query list listeners, unless it is already in the list of media query list listeners.

removeListener (MediaQueryListListener), returns void

When the removeListener operation is invoked listener must be removed from the list of media query list listeners.

interface MediaQueryListListener {
    void handleChange (MediaQueryList list);
};

handleChange (MediaQueryList), returns void

4.2 The Screen Interface

As its name suggests, the Screen interface represents information about the screen of the output device.

interface Screen {
    readonly attribute unsigned long availWidth;
    readonly attribute unsigned long availHeight;
    readonly attribute unsigned long width;
    readonly attribute unsigned long height;
    readonly attribute unsigned long colorDepth;
    readonly attribute unsigned long pixelDepth;
};

availWidth of type unsigned long, readonly

The availWidth attribute must return the available width of the rendering surface of the output device.

availHeight of type unsigned long, readonly

The availHeight attribute must return the available height of the rendering surface of the output device.

width of type unsigned long, readonly

The width attribute must return the width of the output device.

height of type unsigned long, readonly

The height attribute must return the height of the output device.

colorDepth of type unsigned long, readonly

The colorDepth attribute must return the number of bits allocated to colors (i.e. excluding the alpha channel) in the output device. If the output device does not support colors these attributes must return zero.

pixelDepth of type unsigned long, readonly

The pixelDepth attribute must return the value returned by the colorDepth attributed.

5 Extensions to the Document Interface

partial interface Document {
    Element? elementFromPoint (float x, float y);
    CaretPosition? caretPositionFromPoint (float x, float y);
};

elementFromPoint (float, float), returns Element?

The elementFromPoint operation must return the element at coordinates x,y in the viewport. The element to be returned is determined through hit testing. If either argument is negative, x is greater than the viewport width excluding the size of a rendered scroll bar (if any), or y is greater than the viewport height excluding the size of a rendered scroll bar (if any), the method must return null. If there is no element at the given position the method must return the root element, if any, or null otherwise.

caretPositionFromPoint (float, float), returns CaretPosition?

The caretPositionFromPoint operation must return the result of running these steps:

1. If either argument is negative, x is greater than the viewport width excluding the size of a rendered scroll bar (if any), y is greather than the viewport height excluding the size of a rendered scroll bar (if any) return null.

2. If at the coordinates x,y in the viewport no text insertion point indicator would have been inserted return null.

3. If at the coordinates x,y in the viewport a text insertion point indicator would have been inserted in a text entry widget which is also a replaced element return a caret position with its properties set as follows:

   caret node

   The node corresponding to the text entry widget.

   caret offset

   The amount of 16-bit units to the left of where the text insertion point indicator would have inserted.

   caret range

   null

4. Otherwise, return a caret position where the caret range is a collapsed Range object for the position where the text insertion point indicator would have been inserted and the other properties are set as follows:

   caret node

   The startContainer of the caret range.

   caret offset

   The startOffset of the caret range.

The specifics of hit testing are out of scope of this specification and therefore the exact details of elementFromPoint() and caretPositionFromPoint() are therefore too. Hit testing will hopefully be defined in a future revision of CSS or HTML.

5.1 The CaretPosition Interface

A caret position gives the position of a text insertion point indicator. It always has an associated caret node, caret offset, and caret range. It is represented by a CaretPosition interface.

interface CaretPosition {
    readonly attribute Node offsetNode;
    readonly attribute unsigned long offset;
};

offsetNode of type Node, readonly

The offsetNode attribute must return the caret node.

offset of type unsigned long, readonly

The offset attribute must return the caret offset.

6 Extensions to the Element Interface

partial interface Element {
    ClientRectList getClientRects ();
    ClientRect getBoundingClientRect ();
    void scrollIntoView (optional boolean top);
    attribute long scrollTop;
    attribute long scrollLeft;
    readonly attribute long scrollWidth;
    readonly attribute long scrollHeight;
    readonly attribute long clientTop;
    readonly attribute long clientLeft;
    readonly attribute long clientWidth;
    readonly attribute long clientHeight;
};

scrollTop of type long

The scrollTop attribute must return the result of running these steps:

1. If the element does not have any associated CSS layout box or the element is the root element and the Document is in quirks mode return zero and terminate these steps.

2. If the element is the root element return the value of scrollY.

3. If the element is the HTML body element, the Document is in quirks mode, and the element does not have any overflow, return the value of scrollY.

4. Return the y-coordinate of the content at the alignment point with the top of the content edge of the element.

When setting the scrollTop attribute these steps must be run:

1. Let y be the given value.

2. If the element does not have any associated CSS layout box, the element is the root element and the Document is in quirks mode, or the element has no overflow, terminate these steps.

3. If the element is the root element invoke scroll() with zero as first argument and y as second.

4. If the element is the HTML body element, the Document is in quirks mode, and the element does not have any vertical overflow, invoke scroll() with scrollX as first argument and y as second.

5. Scroll the element to scrollLeft,y.

scrollLeft of type long

The scrollLeft attribute must return the result of running these steps:

1. If the element does not have any associated CSS layout box or the element is the root element and the Document is in quirks mode return zero and terminate these steps.

2. If the element is the root element return the value of scrollX.

3. If the element is the HTML body element, the Document is in quirks mode, and the element does not have any overflow, return the value of scrollX.

4. Return the x-coordinate of the content at the alignment point with the left of the content edge of the element.

When setting the scrollLeft attribute these steps must be run:

1. Let x be the given value.

2. If the element does not have any associated CSS layout box, the element is the root element and the Document is in quirks mode, or the element has no overflow, terminate these steps.

3. If the element is the root element invoke scroll() with x as first argument and zero as second.

4. If the element is the HTML body element, the Document is in quirks mode, and the element does not have any vertical overflow, invoke scroll() with x as first argument and scrollY as second.

5. Scroll the element to x,scrollTop.

scrollWidth of type long, readonly

The scrollWidth attribute must return the result of running these steps:

1. If the element does not have any associated CSS layout box return zero and terminate these steps.

2. If the element is the root element and the Document is not in quirks mode return max(document content width, value of innerWidth).

3. If the element is the HTML body element and the Document is in quirks mode return max(document content width, value of innerWidth).

4. Return the computed value of the 'padding-left' property, plus the computed value of the 'padding-right', plus the content width of the element.

scrollHeight of type long, readonly

The scrollHeight attribute must return the result of running these steps:

1. If the element does not have any associated CSS layout box return zero and terminate these steps.

2. If the element is the root element and the Document is not in quirks mode return max(document content height, value of innerHeight).

3. If the element is the HTML body element and the Document is in quirks mode return max(document content height, value of innerHeight).

4. Return the computed value of the 'padding-top' property, plus the computed value of the 'padding-bottom', plus the content height of the element.

clientTop of type long, readonly

The clientTop attribute returns the computed value of the 'border-top-width' property plus the width of any scrollbar rendered between the top padding edge and the top border edge.

clientLeft of type long, readonly

The clientLeft attribute returns the computed value of the 'border-left-width' property plus the width of any scrollbar rendered between the left padding edge and the left border edge.

clientWidth of type long, readonly

The clientWidth attribute returns the viewport width excluding the size of a rendered scroll bar (if any) if the element is the root element and the width of the padding edge (excluding the width of any rendered scrollbar between the padding edge and the border edge) otherwise.

clientHeight of type long, readonly

The clientHeight attribute returns the viewport height excluding the size of a rendered scroll bar (if any) if the element is the root element and the height of the padding edge (excluding the height of any rendered scrollbar between the padding edge and the border edge) otherwise.

getClientRects (), returns ClientRectList

The getClientRects operation, when invoked, must return the result of the following algorithm:

1. If the element on which it was invoked does not have an associated CSS layout box and is not in the http://www.w3.org/2000/svg namespace return an empty ClientRectList object and stop this algorithm.

2. If the element does not have an associated CSS layout box and is in the http://www.w3.org/2000/svg namespace return a ClientRectList object containing a single ClientRect object that describes the bounding box of the element as defined by the SVG specification. [SVG]

3. Return a ClientRectList object containing a list of ClientRect objects in content order describing the border boxes (including those with a height or width of zero) with the following constraints:

   • If the element on which the method was invoked has a computed value for display property of table or inline-table include both the table box and the caption box, if any, but not the anonymous container box.

   • Replace each anonymous block box with its child box(es) and repeat this until no anonymous block boxes are left in the final list.

getBoundingClientRect (), returns ClientRect

The getBoundingClientRect operation, when invoked, must return the result of the following algorithm:

1. Let list be the result of invoking getClientRects() on the same element this method was invoked on.

2. If the list is empty return a ClientRect object whose top, right, bottom and left members are zero.

3. Otherwise, return a ClientRect object describing the smallest rectangle that includes the first rectangle in list and all of the remaining rectangles of which the height or width is not zero.

The following snippet gets the dimensions of the first div element in a document:

var example = document.getElementsByTagName("div")[0].getBoundingClientRect();
var exampleWidth = example.width;
var exampleHeight = example.height;

scrollIntoView (optional boolean), returns void

The must run these steps:

1. If the element does not have any associated CSS layout box terminate these steps.

2. Scroll the element into view with the align to top flag set if top is true or omitted.

6.1 The getClientRects() and getBoundingClientRect() methods

The getClientRects() and getBoundingClientRect() methods provide information about the position of the border box edges of an element relative to the viewport. The objects these methods return must be static. That is, changes to the underlying document are not reflected in the objects.

6.2 Element Scrolling Members

To scroll an element into view, optionally with an align to top flag set, means to run these steps for each ancestor element or viewport that establishes a scrolling box, in order of innermost to outermost scrolling box:

1. If the Document associated with the element to be scrolled into view is not same origin with the Document associated with the element or viewport associated with the scrolling box, terminate these steps.

2. If the align to top flag is set align the top of the border box of the element to be scrolled into view with the top of the scrolling box.

3. Otherwise, if the align to top flag is not set align the bottom of the border box of the element to be scrolled into view with the bottom of the scrolling box.

4. Align the left of the border box of the element to be scrolled into view with the left of the scrolling box.

5. If the aligning did not cause content to move terminate these steps.

6. If the scrolling box is associated with an element

   Queue a task to fire an event named scroll at the element associated with the scrolling box, unless a task to fire that event at that element was already queued.

   If the scrolling box is associated with a viewport

   Queue a task to fire an event named scroll that bubbles at the Document object associated with the viewport, unless a task to fire that event at that Document object was already queued.

To scroll an element to x,y means to:

1. If either x or y is infinite or NaN terminate this algorithm.

2. If the element can have overflow to the right

   Let x be max(0, min(x, content width - content edge width)).

   If the element can have overflow to the left (under right-to-left conditions)

   Let x be min(0, max(x, content edge width - content width)).

3. Let y be max(0, min(y, content height - content edge height)).

4. Align content x-coordinate x with the left of the content edge of the element and align content y-coordinate y with the top of the content edge of the element.

5. If the aligning caused content to move queue a task to fire an event named scroll at the element, unless a task to fire that event at that element was already queued.

6.3 The clientTop, clientLeft, clientWidth, and clientHeight attributes

The clientTop, clientLeft, clientWidth, and clientHeight attributes must return zero if the element does not have any associated CSS layout box or if the CSS layout box is inline. Otherwise, these attributes must behave as defined in the remainder of this section.

7 Extensions to the HTMLElement Interface

partial interface HTMLElement {
    readonly attribute Element offsetParent;
    readonly attribute long offsetTop;
    readonly attribute long offsetLeft;
    readonly attribute long offsetWidth;
    readonly attribute long offsetHeight;
};

offsetParent of type Element, readonly

The offsetParent attribute must return the result of running these steps:

1. If any of the following holds true return null and terminate this algorithm:

   • The element does not have an associated CSS layout box.
   • The element is the root element.
   • The element is the HTML body element.
   • The element's computed value of the 'position' property is fixed.

2. Return the nearest ancestor element of the element for which at least one of the following is true and terminate this algorithm if such an ancestor is found:

   • The computed value of the 'position' property is not static.
   • It is the HTML body element.
   • The computed value of the 'position' property of the element is static and the ancestor is one of the following HTML elements: td, th, or table.

3. Return null.

offsetTop of type long, readonly

The offsetTop attribute must return the result of running these steps:

1. If the element is the HTML body element or does not have any associated CSS layout box return zero and terminate this algorithm.

2. If the offsetParent of the element is null return the y-coordinate of the top border edge of the first CSS layout box associated with the element, relative to the initial containing block origin, and terminate this algorithm.

3. Return the result of subtracting the y-coordinate of the top padding edge of the first CSS layout box associated with the offsetParent of the element from the y-coordinate of the top border edge of the first CSS layout box associated with the element, relative to the initial containing block origin.

   An inline element that consists of multiple line boxes will only have its first CSS layout box considered.

offsetLeft of type long, readonly

The {@name{} attribute must return the result of running these steps:

1. If the element is the HTML body element or does not have any associated CSS layout box return zero and terminate this algorithm.

2. If the offsetParent of the element is null return the x-coordinate of the left border edge of the first CSS layout box associated with the element, relative to the initial containing block origin, and terminate this algorithm.

3. Return the result of subtracting the x-coordinate of the left padding edge of the first CSS layout box associated with the offsetParent of the element from the x-coordinate of the left border edge of the first CSS layout box associated with the element, relative to the initial containing block origin.

offsetWidth of type long, readonly

The offsetWidth attribute must return the result of running these steps:

1. If the element does not have any associated CSS layout box return zero and terminate this algorithm.

2. Return the border edge width of the first CSS layout box associated with the element.

offsetHeight of type long, readonly

The offsetHeight attribute must return the result of running these steps:

1. If the element does not have any associated CSS layout box return zero and terminate this algorithm.

2. Return the border edge height of the first CSS layout box associated with the element.

8 Extensions to the Range Interface

The objects the methods described below return must be static.

partial interface Range {
    ClientRectList getClientRects ();
    ClientRect getBoundingClientRect ();
};

getClientRects (), returns ClientRectList

The getClientRects operation, when invoked, must return an empty ClientRectList object if the range is not in the document and otherwise a ClientRectList object containing a list of ClientRect objects in content order that matches the following constraints:

• For each element selected by the range, whose parent is not selected by the range, include the border boxes returned by invoking getClientRects() on the element.
• For each Text node selected or partially selected by the range (including when the boundary-points are identical), include a ClientRect object (for the part that is selected, not the whole line box). The bounds of these ClientRect objects are computed using font metrics; thus, for horizontal writing, the vertical dimension of each box is determined by the font ascent and descent, and the horizontal dimension by the text advance width.

getBoundingClientRect (), returns ClientRect

The getBoundingClientRect operation, when invoked, must return the result of the following algorithm:

1. Let list be the result of invoking getClientRects() on the same range this method was invoked on.

2. If list is empty return a ClientRect object whose top, right, bottom and left members are zero.

3. Otherwise, return a ClientRect object describing the smallest rectangle that includes the first rectangle in list and all of the remaining rectangles of which the height or width is not zero.

9 Extensions to the MouseEvent Interface

The object IDL fragment redefines some members. Can we resolve this somehow?

partial interface MouseEvent {
    readonly attribute long screenX;
    readonly attribute long screenY;
    readonly attribute long pageX;
    readonly attribute long pageY;
    readonly attribute long clientX;
    readonly attribute long clientY;
    readonly attribute long x;
    readonly attribute long y;
    readonly attribute long offsetX;
    readonly attribute long offsetY;
};

screenX of type long, readonly

The screenX attribute must return the x-coordinate of the position where the event occurred relative to the origin of the screen.

screenY of type long, readonly

The screenY attribute must return the y-coordinate of the position where the event occurred relative to the origin of the screen.

pageX of type long, readonly

The pageX attribute must return the horizontal coordinate of the position where the event occurred relative to the origin of the initial containing block.

pageY of type long, readonly

The pageY attribute must return the y-coordinate of the position where the event occurred relative to the origin of the initial containing block.

clientX of type long, readonly

The clientX attribute must return the x-coordinate of the position where the event occurred relative to the origin of the viewport.

clientY of type long, readonly

The clientY attribute must return the y-coordinate of the position where the event occurred relative to the origin of the viewport.

x of type long, readonly

The x attribute must return the value of clientX.

y of type long, readonly

The y attribute must return the value of clientY.

offsetX of type long, readonly

The offsetX attribute must return the x-coordinate of the position where the event occurred relative to the origin of the padding edge of the target node.

offsetY of type long, readonly

The offsetY attribute must return the y-coordinate of the position where the event occurred relative to the origin of the padding edge of the target node.

10 Rectangles

10.1 The ClientRectList Interface

The ClientRectList interface consists of an ordered list of ClientRect objects.

interface ClientRectList {
    readonly attribute unsigned long length;
    ClientRect item (unsigned long index);
};

length of type unsigned long, readonly

The length attribute must return the total number of ClientRect objects associated with the object.

item (unsigned long), returns ClientRect

The item operation, when invoked, must raise an INDEX_SIZE_ERR exception when index is greater than the number of ClientRect objects associated with the object. Otherwise, the ClientRect object at index must be returned.

10.2 The ClientRect Interface

Objects implementing the ClientRect interface represent a rectangular box. The type of box is specified by the method that returns a ClientRect interface.

interface ClientRect {
    readonly attribute float top;
    readonly attribute float right;
    readonly attribute float bottom;
    readonly attribute float left;
    readonly attribute float width;
    readonly attribute float height;
};

top of type float, readonly

The top attribute must return the y-coordinate, relative to the viewport origin, of the top of the rectangle box.

right of type float, readonly

The right attribute must return the x-coordinate, relative to the viewport origin, of the right of the rectangle box.

bottom of type float, readonly

The bottom attribute must return the y-coordinate, relative to the viewport origin, of the bottom of the rectangle box.

left of type float, readonly

The left attribute must return the x-coordinate, relative to the viewport origin, of the left of the rectangle box.

width of type float, readonly

The width attribute must return the width of the rectangle box.

This is identical to right minus left.

height of type float, readonly

The height attribute must return the height of the rectangle box.

This is identical to bottom minus top.

References

Normative references

Acknowledgments

The editors would like to thank Alexey Feldgendler, Björn Höhrmann, David Vest, Garrett Smith, Hallvord R. M. Steen, Leif Arne Storset, Luiz Agostini, Maciej Stachowiak, Michael Dyck, Mike Wilson, Morten Stenshorne, Peter-Paul Koch, Rachel Kmetz, Robert O'Callahan, Sam Weinig, Simon Pieters, Sylvain Galineau, Tarquin Wilton-Jones, Thomas Moore, and Xiaomei Ji for their contributions to this document.

Special thanks to the Microsoft employees who first implemented many of the features specified in this draft, which were first widely deployed by the Windows Internet Explorer browser.