How to trim specific characters from the end of the JavaScript string?

Question

In JavaScript, how do I trim from the right(string end)?

I have the following example:

var s1 = "this is a test~";
var s = s1.rtrim('~');

Answer 1

Use a RegExp. Don't forget to escape special characters.

s1 = s1.replace(/~+$/, ''); //$ marks the end of a string
                            // ~+$ means: all ~ characters at the end of a string

Answer 2

There are no trim, ltrim, or rtrim functions in Javascript. Many libraries provide them, but generally they will look something like:

str.replace(/~*$/, '');

For right trims, the following is generally faster than a regex because of how regex deals with end characters in most browsers:

function rtrim(str, ch)
{
  let i = str.length;
  while (i-- && str.charAt(i) === ch);
  return str.substring(0, i + 1);
}

console.log(rtrim("moo", "x"));
console.log(rtrim("moo", "o"));
console.log(rtrim("oo", "o"));

Answer 3

You can modify the String prototype if you like. Modifying the String prototype is generally frowned upon, but I personally prefer this method, as it makes the code cleaner IMHO.

String.prototype.rtrim = function(s) { 
    return this.replace(new RegExp(s + "*$"),''); 
};

Then call...

var s1 = "this is a test~";
var s = s1.rtrim('~');
alert(s); 

Answer 4

IMO this is the best way to do a right/left trim and therefore, having a full functionality for trimming (since javascript supports string.trim natively)

String.prototype.rtrim = function (s) {
    if (s == undefined)
        s = '\\s';
    return this.replace(new RegExp("[" + s + "]*$"), '');
};
String.prototype.ltrim = function (s) {
    if (s == undefined)
        s = '\\s';
    return this.replace(new RegExp("^[" + s + "]*"), '');
};

Usage example:

var str1 = '   jav '
var r1 = mystring.trim();      // result = 'jav'
var r2 = mystring.rtrim();     // result = '   jav'
var r3 = mystring.rtrim(' v'); // result = '   ja'
var r4 = mystring.ltrim();     // result = 'jav '

Answer 5

A solution using a regular expression:

"hi there~".replace(/~*$/, "")

Answer 6

str.trimEnd();
str.trimRight();

These are currently stage 4 proposals expected to be part of ES2019. They work in NodeJS and several browsers.

See below for more info:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/trimEnd

Answer 7

This is old, I know. But I don't see what's wrong with substr...?

function rtrim(str, length) {
  return str.substr(0, str.length - length);
}

Answer 8

This removes a specified string or character from the right side of a string

function rightTrim(sourceString,searchString) 
{ 
    for(;;) 
    {
        var pos = sourceString.lastIndexOf(searchString); 
        if(pos === sourceString.length -1)
        {
            var result  = sourceString.slice(0,pos);
            sourceString = result; 
        }
        else 
        {
            break;
        }
    } 
    return sourceString;  
}

Please use like so:

rightTrim('sourcecodes.....','.'); //outputs 'sourcecodes'
rightTrim('aaabakadabraaa','a');   //outputs 'aaabakadabr'

Answer 9

My 2 cents:

function rtrim(str: string, ch: string): string
{
    var i:number = str.length - 1; 
    
    while (ch === str.charAt(i) && i >= 0) i--
    
    return str.substring(0, i + 1);
}

const tests = ["/toto/", "/toto///l/", "/toto////", "/////", "/"]

tests.forEach(test => {
    console.log(`${test} = ${rtrim(test, "/")}`)
})

Gives

"/toto/ = /toto"
"/toto///l/ = /toto///l"
"/toto//// = /toto"
"///// = "
"/ = "

Answer 10

You can add lodash library. It is a JavaScript utility library, There are some trim functions. You can use:

_.trimEnd('this is a test~', '~')