ReactPerf.js

/**
 * Copyright 2013-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule ReactPerf
 */

'use strict';

/**
 * ReactPerf is a general AOP system designed to measure performance. This
 * module only has the hooks: see ReactDefaultPerf for the analysis tool.
 */
var ReactPerf = {
  /**
   * Boolean to enable/disable measurement. Set to false by default to prevent
   * accidental logging and perf loss.
   */
  enableMeasure: false,

  /**
   * Holds onto the measure function in use. By default, don't measure
   * anything, but we'll override this if we inject a measure function.
   */
  storedMeasure: _noMeasure,

  /**
   * @param {object} object
   * @param {string} objectName
   * @param {object<string>} methodNames
   */
  measureMethods: function(object, objectName, methodNames) {
    if (__DEV__) {
      for (var key in methodNames) {
        if (!methodNames.hasOwnProperty(key)) {
          continue;
        }
        object[key] = ReactPerf.measure(
          objectName,
          methodNames[key],
          object[key]
        );
      }
    }
  },

  /**
   * Use this to wrap methods you want to measure. Zero overhead in production.
   *
   * @param {string} objName
   * @param {string} fnName
   * @param {function} func
   * @return {function}
   */
  measure: function(objName, fnName, func) {
    if (__DEV__) {
      var measuredFunc = null;
      var wrapper = function() {
        if (ReactPerf.enableMeasure) {
          if (!measuredFunc) {
            measuredFunc = ReactPerf.storedMeasure(objName, fnName, func);
          }
          return measuredFunc.apply(this, arguments);
        }
        return func.apply(this, arguments);
      };
      wrapper.displayName = objName + '_' + fnName;
      return wrapper;
    }
    return func;
  },

  injection: {
    /**
     * @param {function} measure
     */
    injectMeasure: function(measure) {
      ReactPerf.storedMeasure = measure;
    },
  },
};

/**
 * Simply passes through the measured function, without measuring it.
 *
 * @param {string} objName
 * @param {string} fnName
 * @param {function} func
 * @return {function}
 */
function _noMeasure(objName, fnName, func) {
  return func;
}

module.exports = ReactPerf;