Alex Rivera | Logout

Left Trim in Javascript

Asked 2009-10-20T11:08:13.593
18

There are a lot of scripts out there to trim a string in JavaScript, but none that allow you to just left trim a string.

This is what I use to trim:

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

I would like to change this a little and create a new function called leftTrim that only removes the leading space.

javascript regex trim
Edit
Report

2 Answers

31

Use:

String.prototype.leftTrim = function() {
    return this.replace(/^\s+/,"");
}

In the regex the:

  • ^ means "from the beginning of the string"
  • \s means whitespace character class
  • + means one-or more (greedy)

so....

  • ^\s+ means "one or more consecutive whitespace characters from the beginning of the class"

Note: The g flag at the end of your regex is unnecessary as the anchors (^ and $) explicitly define what will match. There cannot be multiple matches.

See https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/RegExp for details on regex syntax in javascript

answered 2009-10-20T11:10:13.927
1
String.prototype.leftTrim = function() {
        return this.replace(/^\s+/,"");
}
answered 2009-10-20T11:11:10.893

Your Answer