如何在JavaScript中为IE8添加非可枚举属性？ [英] How to add non-enumerable property in JavaScript for IE8?

问题描述

有没有办法将隐藏的不可枚举属性添加到跨浏览器的JavaScript对象？

Is there a way to add "hidden" non-enumerable properties to a JavaScript object that works cross-browser?

对于大多数现代浏览器，您可以执行以下操作：

For most modern browsers, you can do:

Object.defineProperty(obj, '__id__', { enumerable: false, value: id++ });

对于一些没有 Object.defineProperty的旧版非IE浏览器，你可以使用 __ proto __ hack 。

For some older non-IE browsers that don't have Object.defineProperty, you can use the __proto__ hack.

然而，这些都不适用于IE 。有没有办法在IE8中实现这一点（如果IE7也会很酷，但不是必需的）？

None of those, however, work for IE. Is there a way to accomplish this in IE8 (would be cool if IE7 too, but not necessary)?

主要目标是能够向任何人添加跟踪器属性JavaScript {} 对象，但是当你调用 JSON.stringify（obj）时，它不会包括在内在酒店。我意识到你可以添加自定义JSON替换器函数（基本上扩展 JSON.stringify 功能），但我不是那么忠实，因为它意味着你有时候序列化这些将JavaScript对象跟踪为JSON，您必须知道/记得添加替换函数这是非常不切实际的。

The main goal is to be able to add tracker properties to any JavaScript {} object, but such that when you call JSON.stringify(obj), it doesn't get included in the property. I realize you can add custom JSON replacer functions (basically extending the JSON.stringify functionality), but I'm not a big fan of that because it means any time you serialized these tracked JavaScript Objects into JSON, you would have to know/remember to add that replacer function which is pretty impractical.

有没有办法实现这个目标？

Is there any way to accomplish this?

推荐答案

我无法在IE10中的IE8兼容模式下重现它，但是
定义了像toLocaleString这样的属性应该有效，因为 IE8中没有枚举错误。

Well I cannot reproduce it in IE8 compatability mode in IE10 but defining a property like "toLocaleString" should work because of the don't enum bug in IE8.

var uniqueId = function() {
    var dontEnumBug = false;
    var id = 0;

    if( !Object.defineProperty ) {
        var keyVisited = false;
        for( var k in {toLocaleString: 3}) {
            if( k === "toLocaleString" ) {
                keyVisited = true; 
            }
        }
        if( !keyVisited ) {
            dontEnumBug = true;
        }
    }

    return function( obj ) {
        if( dontEnumBug ) {
            obj.toLocaleString = id++;
        }
        else {
            Object.defineProperty(obj, '__id__', { enumerable: false, value: id++ });
        }

    }

})();

您还可以使用isPrototypeOf或propertyIsEnumerable因为这些函数几乎从未被调用过。

You could also use "isPrototypeOf" or "propertyIsEnumerable" as these are also functions that are pretty much never called.

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