support.js
2.96 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
define([], function() {
/** Used for native method references. */
var arrayProto = Array.prototype,
errorProto = Error.prototype,
objectProto = Object.prototype;
/** Native method references. */
var propertyIsEnumerable = objectProto.propertyIsEnumerable,
splice = arrayProto.splice;
/**
* An object environment feature flags.
*
* @static
* @memberOf _
* @type Object
*/
var support = {};
(function(x) {
var Ctor = function() { this.x = x; },
object = { '0': x, 'length': x },
props = [];
Ctor.prototype = { 'valueOf': x, 'y': x };
for (var key in new Ctor) { props.push(key); }
/**
* Detect if `name` or `message` properties of `Error.prototype` are
* enumerable by default (IE < 9, Safari < 5.1).
*
* @memberOf _.support
* @type boolean
*/
support.enumErrorProps = propertyIsEnumerable.call(errorProto, 'message') ||
propertyIsEnumerable.call(errorProto, 'name');
/**
* Detect if `prototype` properties are enumerable by default.
*
* Firefox < 3.6, Opera > 9.50 - Opera < 11.60, and Safari < 5.1
* (if the prototype or a property on the prototype has been set)
* incorrectly set the `[[Enumerable]]` value of a function's `prototype`
* property to `true`.
*
* @memberOf _.support
* @type boolean
*/
support.enumPrototypes = propertyIsEnumerable.call(Ctor, 'prototype');
/**
* Detect if properties shadowing those on `Object.prototype` are non-enumerable.
*
* In IE < 9 an object's own properties, shadowing non-enumerable ones,
* are made non-enumerable as well (a.k.a the JScript `[[DontEnum]]` bug).
*
* @memberOf _.support
* @type boolean
*/
support.nonEnumShadows = !/valueOf/.test(props);
/**
* Detect if own properties are iterated after inherited properties (IE < 9).
*
* @memberOf _.support
* @type boolean
*/
support.ownLast = props[0] != 'x';
/**
* Detect if `Array#shift` and `Array#splice` augment array-like objects
* correctly.
*
* Firefox < 10, compatibility modes of IE 8, and IE < 9 have buggy Array
* `shift()` and `splice()` functions that fail to remove the last element,
* `value[0]`, of array-like objects even though the "length" property is
* set to `0`. The `shift()` method is buggy in compatibility modes of IE 8,
* while `splice()` is buggy regardless of mode in IE < 9.
*
* @memberOf _.support
* @type boolean
*/
support.spliceObjects = (splice.call(object, 0, 1), !object[0]);
/**
* Detect lack of support for accessing string characters by index.
*
* IE < 8 can't access characters by index. IE 8 can only access characters
* by index on string literals, not string objects.
*
* @memberOf _.support
* @type boolean
*/
support.unindexedChars = ('x'[0] + Object('x')[0]) != 'xx';
}(1, 0));
return support;
});