Spinner: Fixed precision when stepping.

Thanks hughlomas

Author: scottgonzalez

tests/unit/spinner/spinner_core.js

@@ -185,4 +185,21 @@ test( "focus text field when pressing button", function() {
 	ok( element[ 0 ] === document.activeElement, "focused after" );
 });
 
+test( "precision", function() {
+	expect( 2 );
+	var element = $( "#spin" ).spinner({
+		value: .05,
+		step: .0001
+	});
+	element.spinner( "stepUp" );
+	equal( element.val(), "0.0501", "precision from step" );
+
+	element.spinner( "option", {
+		value: 1.05,
+		step: 1
+	});
+	element.spinner( "stepDown" );
+	equal( element.val(), "0.05", "precision from value" );
+});
+
 })( jQuery );

ui/jquery.ui.spinner.js

@@ -228,10 +228,13 @@ $.widget( "ui.spinner", {
 			this.counter = 1;
 		}
 
-		var newVal = this.value() + step * this._increment( this.counter );
+		var newVal = this.value() + step * this._increment( this.counter ),
+			// fix precision from bad JS floating point math
+			precision = Math.max( this._precision( this.value() ),
+				this._precision( this.options.step ) );
 
 		// clamp the new value
-		newVal = this._trimValue( newVal );
+		newVal = this._trimValue( newVal.toFixed( precision ) );
 
 		if ( !this.spinning || this._trigger( "spin", event, { value: newVal } ) !== false) {
 			this._value( newVal );
@@ -245,6 +248,12 @@ $.widget( "ui.spinner", {
 			1;
 	},
 
+	_precision: function( num ) {
+		var str = num.toString(),
+			decimal = str.indexOf( "." );
+		return decimal === -1 ? 0 : str.length - decimal - 1;
+	},
+
 	_trimValue: function( value ) {
 		var options = this.options;