如何替换除第一个匹配项外的所有匹配字符 [英] How to replace all matching characters except the first occurrence

问题描述

我正在尝试使用正则表达式比较JavaScript中的字符串.我想用空字符''替换所有'.'s和'%'s，但是要注意的是我不想替换第一次出现的'.'.

value.replace(/\%\./g, '');

预期结果如下:

.4.5.6.7. ==> .4567
4.5667.444... ==> 4.56667444
..3445.4 ==> .34454

解决方案

您可以将函数传递给replace，并跳过第一个匹配项，如下所示:

var i = 0;
value.replace(/[\.\%]/g, function(match) { 
    return match === "." ? (i++ === 0 ? '.' : '') : ''; 
});

---

这是一个没有外部变量的独立版本:

value.replace(/[\.\%]/g, function(match, offset, all) { 
   return match === "." ? (all.indexOf(".") === offset ? '.' : '') : ''; 
}) 

第二个版本使用传递到replace()函数中的offset与原始字符串(all)中找到的第一个.的索引进行比较.如果它们相同，则正则表达式将其保留为..后续匹配的偏移量将比第一个匹配的.偏移量高，并且将替换为''. %将始终替换为''.

---

两个版本均导致:

4.5667.444 ... ==> 4.56667444
％4.5667.444 ... ==> 4.5667444

两个版本的演示: http://jsbin.com/xuzoyud/5/

I am trying to use regex to compare a string in JavaScript. I want to replace all '.'s and '%'s with empty character '' but the catch is I don't want to replace the first occurrence of '.'.

value.replace(/\%\./g, '');

Expected result like below:

.4.5.6.7. ==> .4567
4.5667.444... ==> 4.56667444
..3445.4 ==> .34454

解决方案

You can pass in a function to replace, and skip the first match like this:

var i = 0;
value.replace(/[\.\%]/g, function(match) { 
    return match === "." ? (i++ === 0 ? '.' : '') : ''; 
});

---

Here is a self-contained version with no external variables:

value.replace(/[\.\%]/g, function(match, offset, all) { 
   return match === "." ? (all.indexOf(".") === offset ? '.' : '') : ''; 
}) 

This second version uses the offset passed into the replace() function to compare against the index of the first . found in the original string (all). If they are the same, the regex leaves it as a .. Subsequent matches will have a higher offset than the first . matched, and will be replaced with a ''. % will always be replaced with a ''.

---

Both versions result in:

4.5667.444... ==> 4.56667444
%4.5667.444... ==> 4.5667444

Demo of both versions: http://jsbin.com/xuzoyud/5/

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