modernizr/src/hasOwnProp.js

Modernizr is a JavaScript library that detects HTML5 and CSS3 features in the user’s browser.

define(['is'], function(is) {
  /**
   * hasOwnProp is a shim for hasOwnProperty that is needed for Safari 2.0 support
   *
   * @author kangax
   * @access private
   * @function hasOwnProp
   * @param {object} object - The object to check for a property
   * @param {string} property - The property to check for
   * @returns {boolean}
   */

  // hasOwnProperty shim by kangax needed for Safari 2.0 support
  var hasOwnProp;

  (function() {
    var _hasOwnProperty = ({}).hasOwnProperty;
    /* istanbul ignore else */
    /* we have no way of testing IE 5.5 or safari 2,
     * so just assume the else gets hit */
    if (!is(_hasOwnProperty, 'undefined') && !is(_hasOwnProperty.call, 'undefined')) {
      hasOwnProp = function(object, property) {
        return _hasOwnProperty.call(object, property);
      };
    }
    else {
      hasOwnProp = function(object, property) { /* yes, this can give false positives/negatives, but most of the time we don't care about those */
        return ((property in object) && is(object.constructor.prototype[property], 'undefined'));
      };
    }
  })();

  return hasOwnProp;
});