表达式周围的方括号是什么意思，例如var x = a + [b]`? [英] What do square brackets around an expression mean, e.g. `var x = a + [b]`?

问题描述

我们从一家代理商那里收到了一些JavaScript，该JavaScript看起来不对，但是可以正常工作.

We have received some JavaScript from an agency that looks wrong, but works.

出于某种原因，他们在变量周围添加了方括号([，])，如下所示:

For some reason they are adding square brackets ([, ]) around variables, like this:

var some_variable = 'to=' + [other_variable];

这可行，但是方括号似乎完全多余了.

This works, but the square brackets seem completely superfluous.

是否有使用此语法的目的，或者在技术上不正确，但被浏览器忽略了?

Is there a purpose of using this syntax or is it technically incorrect, but ignored by the browser?

推荐答案

方括号表示新的数组.

var ar=new Array("a","b");
var ar=["a","b"]; //Equal to the syntax above

在这种情况下，是否使用方括号没有什么区别，因为如果它是数组，则将其转换为字符串，但是如果删除方括号，则将花费较少的时间，因为它不必构建新的数组并进行转换它，但它可以与一个简单的字符串一起工作.

in that situation there's no difference if you use square brackets or not because if it's an array it is converted to string, but if you delete the brackets it takes less time because it doesn't have to build a new array and convert it but it works with a simple string.

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