lodash/support.js

define(['./lang/isNative', './internal/root'], function(isNative, root) {

  /** Used to detect functions containing a `this` reference. */
  var reThis = /\bthis\b/;

  /** Used for native method references. */
  var objectProto = Object.prototype;

  /** Used to detect DOM support. */
  var document = (document = root.window) && document.document;

  /** Native method references. */
  var propertyIsEnumerable = objectProto.propertyIsEnumerable;

  /**
   * An object environment feature flags.
   *
   * @static
   * @memberOf _
   * @type Object
   */
  var support = {};

  (function(x) {

    /**
     * Detect if functions can be decompiled by `Function#toString`
     * (all but Firefox OS certified apps, older Opera mobile browsers, and
     * the PlayStation 3; forced `false` for Windows 8 apps).
     *
     * @memberOf _.support
     * @type boolean
     */
    support.funcDecomp = !isNative(root.WinRTError) && reThis.test(function() { return this; });

    /**
     * Detect if `Function#name` is supported (all but IE).
     *
     * @memberOf _.support
     * @type boolean
     */
    support.funcNames = typeof Function.name == 'string';

    /**
     * Detect if the DOM is supported.
     *
     * @memberOf _.support
     * @type boolean
     */
    try {
      support.dom = document.createDocumentFragment().nodeType === 11;
    } catch(e) {
      support.dom = false;
    }

    /**
     * Detect if `arguments` object indexes are non-enumerable.
     *
     * In Firefox < 4, IE < 9, PhantomJS, and Safari < 5.1 `arguments` object
     * indexes are non-enumerable. Chrome < 25 and Node.js < 0.11.0 treat
     * `arguments` object indexes as non-enumerable and fail `hasOwnProperty`
     * checks for indexes that exceed their function's formal parameters with
     * associated values of `0`.
     *
     * @memberOf _.support
     * @type boolean
     */
    try {
      support.nonEnumArgs = !propertyIsEnumerable.call(arguments, 1);
    } catch(e) {
      support.nonEnumArgs = true;
    }
  }(0, 0));

  return support;
});