独立的JavaScript块有什么用吗? [英] Do standalone JavaScript blocks have any use?

问题描述

关于JavaScript块的 MDN文章给出以下示例:

The MDN article on JavaScript blocks gives this example:

var x = 1;
{
  var x = 2;
}
alert(x); // outputs 2

如您所见，JavaScript没有阻止范围.那么JavaScript中的独立块有没有很好的用例?

As you can see JavaScript doesn't have block scope. So are there any good use cases for standalone blocks in JavaScript?

独立"是指不与控制流语句(if，for，while等)或function配对.

By "standalone" I mean not paired with a control flow statement (if, for, while, etc.) or a function.

推荐答案

简短的回答:...不是真的.

我对它们唯一了解的用途是标签:

Short answer: ...not really.

The only use I know for them is labels:

myBlock: {
    // stuff
    if (something) break myBlock // jump to end of block
    // more stuff
    if (somethingElse) continue myBlock // jump to beginning of block
    // blah blah blah, more stuff
}

(几乎像goto，更好的提防猛禽)

不用说，这是一个非常糟糕的主意.因此，基本上，什么都没有；只是不要使用它们.

Needless to say, this is a very bad idea. So basically, nothing; just don't use them.

(旁注:do { /* stuff */ if (something) break; /* stuff */ } while (false)可以做同样的事情)

(side note: a do { /* stuff */ if (something) break; /* stuff */ } while (false) could do the same thing)

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