Trim function JavaScript/JScript

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I needed to trim a string and also replace more than one spaces with a single space. The solution was simple with String.replace in JavaScript. Here's the code:

var m = " My name  is Pradeep ";
m = m.replace(/^[\s]+/,'').replace(/[\s]+$/,'').replace(/[\s]{2,}/,' ');

Making a function out of it.

function trim(str)
{
    if(!str || typeof str != 'string')
        return null;

    return str.replace(/^[\s]+/,'').replace(/[\s]+$/,'').replace(/[\s]{2,}/,' ');
}

[Parimal]

great

[urstop]

Good use of regular expressions, we wish there was a simpler method like vbscript where in we can just use the function trim.

[prasanna_gg]

Hi Pradeep,

Nice solution. Although it could be extended nicely so it works natively in Javascript. JS provides a way to create prototype functions easily.

Here is the code:

String.prototype.trim = function() {  return this.replace(/^\s+|\s+$/g, '');  }

This method can be called like any in-built javascript function - string.trim() instead of trim(string)!

[gkumar]

Use the code below to make trim a method of all Strings. These are useful to place in a global Javascript file included by all your pages.

String.prototype.trim = function() {
	return this.replace(/^\s+|\s+$/g,"");
}
String.prototype.ltrim = function() {
	return this.replace(/^\s+/,"");
}
String.prototype.rtrim = function() {
	return this.replace(/\s+$/,"");
}

// example of using trim, ltrim, and rtrim
var myString = " hello my name is ";
alert("*"+myString.trim()+"*");
alert("*"+myString.ltrim()+"*");
alert("*"+myString.rtrim()+"*");

Javascript Trim Stand-Alone Functions:-If you prefer not to modify the string prototype, then you can use the stand-alone functions below.

function trim(stringToTrim) {
	return stringToTrim.replace(/^\s+|\s+$/g,"");
}
function ltrim(stringToTrim) {
	return stringToTrim.replace(/^\s+/,"");
}
function rtrim(stringToTrim) {
	return stringToTrim.replace(/\s+$/,"");
}

// example of using trim, ltrim, and rtrim
var myString = " hello my name is ";
alert("*"+trim(myString)+"*");
alert("*"+ltrim(myString)+"*");
alert("*"+rtrim(myString)+"*");

[pradeep]

Nice one gkumar