ECMAScript 6 中的 Symbol.for(string) [英] Symbol.for(string) in ECMAScript 6

问题描述

我花了一段时间，但我终于弄清楚了 ECMAScript 6 中符号的目的是什么:在将属性附加到共享对象时避免名称冲突 - HTML 元素，例如(如果您遇到同样的问题，我推荐这篇文章.)

It took me a while but I finally figured out what the purpose of symbols in ECMAScript 6 is: avoiding name collision when attaching properties to shared objects - HTML elements e.g. (In case you're stuck on the same question, I recommend this article.)

但后来我偶然发现了Symbol.for().显然 ECMAScript 6 将维护一个全局符号注册表，您可以通过提供符号描述来使用此函数进行查询.再来?如果我使用符号来避免名称冲突，我为什么要使用我自己以外的代码来使用它们?(*) 我将如何避免该全局注册表中的名称冲突?符号的共享似乎完全颠覆了这个概念，而全球注册也是如此.

But then I stumbled upon Symbol.for(). Apparently ECMAScript 6 will maintain a global symbol registry which you can query with this function by providing the symbol description. Come again? If I use symbols to avoid name collisions, why would I want code other than my own to use them? (*) And how would I avoid name collisions in that global registry? Sharing of symbols seems to completely subvert the concept and a global registry doubly so.

(*) 是的，我知道符号不是真正私有的，但这不是重点.

(*) Yes, I know symbols aren't truly private, but that's besides the point.

推荐答案

如果您不希望您的符号在 GlobalSymbolRegistry 中可用，请不要使用 Symbol.for.

If you don't want your symbols to be available in GlobalSymbolRegistry, just don't use Symbol.for.

仅当您想让其他代码使用您的符号时才使用它.

Only use it if you want to allow other codes to use your symbol.

在下面的示例中，我创建了一个符号来在 DOM 元素中存储数据.我可能想要所有其他代码(例如 内部原始未编译处理程序)读取该数据.所以我让符号全局可用.

In the following example, I create a symbol to store data in DOM elements. And I may want every other code (e.g. internal raw uncompiled handlers) to read that data. So I make the symbol globally available.

var sym = Symbol.for('storeDataInDOM');
document.querySelector('button')[sym] = 'Hello, world!';

<button onclick="alert(this[Symbol.for('storeDataInDOM')])">Click me</button>

这就像创建全局变量:一般应该避免，但有其优点.但是用符号代替字符串.

It's like creating global variables: should be avoided in general, but has its advantages. But with symbols instead of strings.

这篇关于ECMAScript 6 中的 Symbol.for(string)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！