javascript 从字符串中删除最后一个逗号

Remove Last Comma from a string

提问by AnaMaria

Using JavaScript, how can I remove the last comma, but only if the comma is the last character or if there is only white space after the comma? This is my code. I got a working fiddle. But it has a bug.

使用 JavaScript，如何删除最后一个逗号，但前提是逗号是最后一个字符或者逗号后只有空格？这是我的代码。我得到了一个工作小提琴。但它有一个错误。

var str = 'This, is a test.'; 
alert( removeLastComma(str) ); // should remain unchanged

var str = 'This, is a test,'; 
alert( removeLastComma(str) ); // should remove the last comma

var str = 'This is a test,          '; 
alert( removeLastComma(str) ); // should remove the last comma

function removeLastComma(strng){        
    var n=strng.lastIndexOf(",");
    var a=strng.substring(0,n) 
    return a;
}

回答by Jon

This will remove the last comma and any whitespace after it:

这将删除最后一个逗号和它后面的任何空格：

str = str.replace(/,\s*$/, "");

It uses a regular expression:

它使用正则表达式：

• The /mark the beginning and end of the regular expression

• The ,matches the comma

• The \smeans whitespace characters (space, tab, etc) and the *means 0 or more

• The $at the end signifies the end of the string

• 该/标记的开始和正则表达式的结束

• 该,逗号匹配

• 该\s装置的空白字符（空格，制表符，等），和*装置0以上

• 将$在最后表示该字符串的结尾

回答by e-techpulse

you can remove last comma from a string by using slice() method, find the below example:

您可以使用 slice() 方法从字符串中删除最后一个逗号，找到以下示例：

var strVal = $.trim($('.txtValue').val());
var lastChar = strVal.slice(-1);
if (lastChar == ',') {
    strVal = strVal.slice(0, -1);
}

Here is an Example

这是一个例子

function myFunction() {
 var strVal = $.trim($('.txtValue').text());
 var lastChar = strVal.slice(-1);
 if (lastChar == ',') { // check last character is string
  strVal = strVal.slice(0, -1); // trim last character
  $("#demo").text(strVal);
 }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>


<p class="txtValue">Striing with Commma,</p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

回答by Daniel Sloof

function removeLastComma(str) {
   return str.replace(/,(\s+)?$/, '');   
}

回答by Daniel Sloof

long shot here

远射在这里

var sentence="I got,. commas, here,";
var pattern=/,/g;
var currentIndex;
while (pattern.test(sentence)==true)  {    
  currentIndex=pattern.lastIndex;
 }
if(currentIndex==sentence.trim().length)
alert(sentence.substring(0,currentIndex-1));
else
 alert(sentence);

回答by Booboo

The greatly upvoted answer removes not only the final comma, but also any spaces that follow. But removing those following spaces was notwhat was part of the original problem. So:

大大赞成的答案不仅删除了最后一个逗号，还删除了后面的任何空格。但是删除后面的空格并不是原始问题的一部分。所以：

let str = 'abc,def,ghi, ';
let str2 = str.replace(/,(?=\s*$)/, '');
alert("'" + str2 + "'");
'abc,def,ghi '

https://jsfiddle.net/dc8moa3k/

https://jsfiddle.net/dc8moa3k/

回答by Max Alexander Hanna

First, one should check if the last character is a comma. If it exists, remove it.

首先，应该检查最后一个字符是否是逗号。如果存在，请将其删除。

if (str.indexOf(',', this.length - ','.length) !== -1) {
    str = str.substring(0, str.length - 1);
}

NOTEstr.indexOf(',', this.length - ','.length) can be simplified to str.indexOf(',', this.length - 1)

注意str.indexOf(',', this.length - ','.length) 可以简化为 str.indexOf(',', this.length - 1)

回答by Hristo Valkanov

The problem is that you remove the last comma in the string, not the comma if it's the last thing in the string. So you should put an if to check if the last char is ',' and change it if it is.

问题是您删除了字符串中的最后一个逗号，而不是删除了字符串中最后一个逗号的逗号。因此，您应该放置一个 if 来检查最后一个字符是否为 ',' ，如果是则更改它。

EDIT: Is it really that confusing?

编辑：真的那么令人困惑吗？

'This, is a random string'

'这是一个随机字符串'

Your code finds the last comma from the string and stores only 'This, ' because, the last comma is after 'This' not at the end of the string.

您的代码从字符串中找到最后一个逗号并仅存储 'This, ' 因为最后一个逗号在 'This' 之后而不是在字符串的末尾。

回答by Deepu Reghunath

Remove last comma. Working example

删除最后一个逗号。工作示例

function truncateText() {
  var str= document.getElementById('input').value;
  str = str.replace(/,\s*$/, "");
  console.log(str);
}

<input id="input" value="address line one,"/>
<button onclick="truncateText()">Truncate</button>

回答by Trai H?i Phòng

you can remove last comma:

您可以删除最后一个逗号：

var sentence = "I got,. commas, here,";
sentence = sentence.replace(/(.+),$/, '');
console.log(sentence);