从字符串中删除最后一个逗号

Question

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.

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;
}

Answer 1

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

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

It uses a regular expression:

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

• The , matches the comma

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

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

Answer 2

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

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

Here is an Example

 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>

Answer 3

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

Answer 4

In case its useful or a better way:

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

It will replace all following combination end of the string:

1. ,<no space>
2. ,<spaces> 
3. ,  ,  , ,   ,
4. <spaces>
5. <spaces>,
6. <spaces>,<spaces>

Answer 5

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

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

https://jsfiddle.net/dc8moa3k/

Answer 6

long shot here

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);

Answer 7

you can remove last comma:

var sentence = "I got,. commas, here,";
sentence = sentence.replace(/(.+),$/, '$1');
console.log(sentence);

Answer 8

Remove last comma. Working example

 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>

Answer 9

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

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

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

Answer 10

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.

EDIT: Is it really that confusing?

'This, is a random string'

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.

Answer 11

A late answer but probably should help someone.

For removing any last char from a string.

 var str = "one, two, three,"; var str2 = str.substring(0, str.length - 1); alert(str); alert(str2); 

Answer 12

With or without Regex.

I suggest two processes and also consider removing space as well. Today I got this problem and I fixed this by writing the below code.

I hope this code will help others.

 //With the help of Regex var str = " I am in Pakistan, I am in India, I am in Japan, "; var newstr = str.replace(/[, ]+$/, "").trim(); console.log(newstr); //Without Regex function removeSpaceAndLastComa(str) { var newstr = str.trim(); var tabId = newstr.split(","); strAry = []; tabId.forEach(function(i, e) { if (i != "") { strAry.push(i); } }) console.log(strAry.join(",")); } removeSpaceAndLastComa(str);

Answer 13

If you are targeting es6, then you can simply do this

str = Array.from( str ).splice(0, str.length - 1).join('');

• This Array.from(str) converts the string to an array (so we can slice it)

• This splice( 0 , str.length - 1 ) returns an array with the items from the array sequentially except the last item in the array

• This join('') joins the entries in the array to form a string

Then if you want to make sure that a comma actually ends the string before performing the operation, you can do something like this

str = str.endsWith(',') ? Array.from(str).splice(0,str.length - 1).join('') : str;

Answer 14

To remove the last comma from a string, you need

text.replace(/,(?=[^,]*$)/, '')
text.replace(/,(?![^,]*,)/, '')

See the regex demo . Details :

• ,(?=[^,]*$) - a comma that is immediately followed with any zero or more chars other than a comma till end of string.
• ,(?![^,]*,) - a comma that is not immediately followed with any zero or more chars other than a comma and then another comma.

See the JavaScript demo:

 const text = '1,This is a test, and this is another, ...'; console.log(text.replace(/,(?=[^,]*$)/, '')); console.log(text.replace(/,(?![^,]*,)/, ''));