为什么仍然使用分号的for循环仍然执行? [英] Why does a for loop with a semicolon after it still execute?

问题描述

我正在看一个朋友做的一些代码，偶然发现这条线，我认为这是一个错误(例如，经过简化).

I was having a look at some code a friend did and stumbled across this line which I thought was an error (simplified for example)..

for (g = 0; 10 > g; g++); {

    alert(g);
}

但是它仍然执行，并警告"10".为什么是这样?这是javascript中的专用函数吗?

However it still executes, and alerts "10". Why is this? Is this a purpose built function in javascript?

JS小提琴

推荐答案

您的 g 变量位于全局上下文中，因此可以在 for 循环之外进行访问.循环完成了它的工作，并增加了 g 十次.
两个 {} 表示JavaScript中的一个块，不会引起任何错误.

Your g variable is within the global context, so it is accessible outside of a for loop. The loop did its job, and incremented g 10 times.
Two {} indicate a block in JavaScript and won't cause any error.

编辑:由于未定义 g 变量，因此没有 for 循环不会警告任何内容.

Edit: it is not alerting anything without a for loop, because the g variable is not defined.

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