将行首的所有制表符匹配并替换为四个空格 [英] Match and replace all tabs at the beginning of the line with four spaces

问题描述

我在网站上还阅读了其他一些问题和答案，但是所有这些问题和答案都与我要查找的内容略有不同:用四个空格替换字符串开头的所有制表符.

I've read some other questions and answers on the site, but all of them were a little different from what I'm seeking: replace all tabs at the beginning of a string with four spaces.

到目前为止我已经尝试过的:

What I've tried so far:

let m = '\t\tsomething\t'

使用/\t/g查找选项卡并不困难，但这将获得不在行首的选项卡.因此，使用m.match(/(\t\W)/)可以解决上面的示例，导致2个匹配项.

Finding tabs isn't hard with /\t/g, but this would get tabs that are not at the beginning of a line. So using m.match(/(\t\W)/) does the trick for the sample above, resulting in 2 matches.

但是使用m.replace(/(\t\W)/, ' ')时，预期结果将是:

But when using m.replace(/(\t\W)/, ' '), the expected result would be:

        something // 8 spaces (4 for each \t)

但是我却得到了:

    something // 4 spaces for two tabs.

为什么这一次只能替换两个标签?以及如何用所需的字符串替换每次出现的\t?

Why is this replacing both tabs just one time? And how can I replace every occurrence of \t with the desired string?

推荐答案

首先，您要同时替换两个制表符和一个非单词字符，这些字符不一定是制表符，必须用四个空格代替.您没有分别匹配每个\t字符.

First off, you are replacing both tabs and a non-word character which may not be a tab character necessarily with four spaces. You are not matching each \t character separately.

将所有制表符替换为字符串开头的四个空格

replace all tabs at the beginning of a string with four spaces

您可以使用 y标志:

You could use y flag:

console.log(
  "\t\tHello, world!".replace(/\t/gy, '    ')
);

或不使用y修饰符(以支持古老的浏览器)，则可以使用一些代码:

or without using y modifier (to support ancient browsers) you could go with a little more bit of code:

console.log(
  "\t\tHello, world!\t".replace(/\t|(.+)/gs, function(match, p1) {
      return p1 ? p1 : '    ';
  })
);

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