主要浏览器中仍然存在ECMAScript 3实现差异吗？ [英] Are there still ECMAScript 3 implementation differences in major browsers?

问题描述

有人可以指出在今天的浏览器中实现ECMAScript第三版的差异吗？ （Chrome，Safari，IE8，FF）

Can someone point out the differences in implementation of ECMAScript 3rd edition in today's browsers? (Chrome, Safari, IE8, FF)

使用ECMAScript 3标准（而不是FF和IE对JScript和JavaScript的扩展） p>

Are we safe when using ECMAScript 3 standards (and not the extensions that FF and IE have to JScript and JavaScript)?

推荐答案

当然，有一些实现错误，最严重的是我不得不处理的是JScript，Microsoft实现的标准，例如：

Well, of course there are implementation bugs, the most serious that I've had to deal with are on JScript, the Microsoft implementation of the standard, for example:

FunctionExpressions的标识符应该只能在函数本身的内部范围内访问：

Identifier of FunctionExpressions should be accessible only in the inner scope of the function itself:

(function foo() {
  alert(typeof foo); // "function"
})();

alert(typeof foo);  // should be "undefined", on IE shows "function"

IE版本，它刚刚修复在IE9预览。

The bug is present on all current IE versions, it has just been fixed on IE9 Previews.

实际上更糟糕的是，它创建两个函数对象，例如：

And actually is even worse, it creates two function objects, for example:

var foo = function bar() {};

if (typeof bar != 'undefined') { // the case of IE
  alert(foo === bar); // false!!!
}

另一个众所周知的JScript错误是DontEnum Bug，如果其范围链中的对象包含不可枚举的属性（具有 { DontEnum} 属性），如果属性被遮蔽在其他对象上，它将保持不可枚举，例如：

Another well known JScript bug is the "DontEnum Bug", if an object in its scope chain contains a property that is not enumerable (has the { DontEnum } attribute), if the property is shadowed on other object, it will stay as non-enumerable, for example:

var dontEnumBug = {toString:'foo'}.propertyIsEnumerable('toString');

它将在IE上评估为 false 这会导致使用 for-in 语句时出现问题，因为将不会访问这些属性。

It will evaluate to false on IE, this causes problems when using the for-in statement, because the properties will not be visited.

推荐文章：

• 与ES3的JScript差异 _pdf

• JScript deviations from ES3_pdf

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