javascript 删除除最后一个之外的所有事件？

Remove all occurrences except last?

提问by lisovaccaro

I want to remove all occurrences of substring = .in a string except the last one.

我想删除.除最后一个之外的字符串中所有出现的 substring = 。

E.G:

例如：

1.2.3.4

should become:

应该变成：

123.4

采纳答案by ninjagecko

2-liner:

2 班轮：

function removeAllButLast(string, token) {
    /* Requires STRING not contain TOKEN */
    var parts = string.split(token);
    return parts.slice(0,-1).join('') + token + parts.slice(-1)
}

Alternative version without the requirement on the string argument:

不需要字符串参数的替代版本：

function removeAllButLast(string, token) {
    var parts = string.split(token);
    if (parts[1]===undefined)
        return string;
    else
        return parts.slice(0,-1).join('') + token + parts.slice(-1)
}

Demo:

演示：

> removeAllButLast('a.b.c.d', '.')
"abc.d"

The following one-liner is a regular expression that takes advantage of the fact that the *character is greedy, and that replace will leave the string alone if no match is found. It works by matching [longest string including dots][dot] and leaving [rest of string], and if a match is found it strips all '.'s from it:

下面的单行是一个正则表达式，它利用了*字符贪婪的事实，如果没有找到匹配，替换将保留字符串。它的工作原理是匹配 [最长的字符串，包括点][点] 并留下 [字符串的其余部分]，如果找到匹配项，它会从中删除所有 '.'：

'a.b.c.d'.replace(/(.*)\./, x => x.replace(/\./g,'')+'.')

(If your string contains newlines, you will have to use [.\n]rather than naked .s)

（如果你的字符串包含换行符，你将不得不使用[.\n]而不是naked .s）

回答by Сухой27

You can use regex with positive look ahead,

您可以使用正则表达式来积极展望，

"1.2.3.4".replace(/[.](?=.*[.])/g, "");

回答by icyrock.com

You can do something like this:

你可以这样做：

var str = '1.2.3.4';
var last = str.lastIndexOf('.');
var butLast = str.substring(0, last).replace(/\./g, '');
var res = butLast + str.substring(last);

Live example:

现场示例：

• http://jsfiddle.net/qwjaW/

• http://jsfiddle.net/qwjaW/

回答by Nina Scholz

You could take a positive lookahead (for keeping the last dot, if any) and replace the first coming dots.

您可以积极向前看（保留最后一个点，如果有的话）并替换第一个出现的点。

var string = '1.2.3.4';

console.log(string.replace(/\.(?=.*\.)/g, ''));

回答by kennebec

var s='1.2.3.4';

var s='1.2.3.4';

s=s.split('.');
s.splice(s.length-1,0,'.');
s.join('');

123.4

123.4

回答by danday74

A replaceAllButLastfunction is more useful than a removeAllButLastfunction. When you want to remove just replace with an empty string:

一个replaceAllButLast功能是多了一个有用的removeAllButLast功能。当您想删除时，只需用空字符串替换即可：

function replaceAllButLast(str, pOld, pNew) {
  var parts = str.split(pOld)
  if (parts.length === 1) return str
  return parts.slice(0, -1).join(pNew) + pOld + parts.slice(-1)
}

var test = 'hello there hello there hello there'
test = replaceAllButLast(test, ' there', '')

console.log(test) // hello hello hello there

回答by danday74

Found a much better way of doing this. Here is replaceAllButLastand appendAllButLastas they should be done. The latter does a replace whilst preserving the original match. To remove, just replace with an empty string.

找到了一个更好的方法来做到这一点。这里是replaceAllButLast和appendAllButLast他们应该做的。后者在保留原始匹配的同时进行替换。要删除，只需替换为空字符串。

var str = "hello there hello there hello there"

function replaceAllButLast(str, regex, replace) {
  var reg = new RegExp(regex, 'g')
  return str.replace(reg, function(match, offset, str) {
      var follow = str.slice(offset);
      var isLast = follow.match(reg).length == 1;
      return (isLast) ? match : replace
  })
}

function appendAllButLast(str, regex, append) {
  var reg = new RegExp(regex, 'g')
  return str.replace(reg, function(match, offset, str) {
      var follow = str.slice(offset);
      var isLast = follow.match(reg).length == 1;
      return (isLast) ? match : match + append
  })
}

var replaced = replaceAllButLast(str, / there/, ' world')
console.log(replaced)

var appended = appendAllButLast(str, / there/, ' fred')
console.log(appended)

Thanks to @leaf for these masterpieces which he gave here.

感谢@leaf在这里提供了这些杰作。

回答by Marc

function formatString() {
  var arr = ('1.2.3.4').split('.');
  var arrLen = arr.length-1;
  var outputString = '.' + arr[arrLen];
  for (var i=arr.length-2; i >= 0; i--) {
     outputString = arr[i]+outputString;
  }
  alert(outputString);
}

See it in action here: http://jsbin.com/izebay

在这里查看它的实际效果：http: //jsbin.com/izebay

回答by swapz83

You could reverse the string, remove all occurrences of substring except the first, and reverse it again to get what you want.

您可以反转字符串，删除除第一个之外的所有子字符串，然后再次反转它以获得您想要的。