Question

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.

Answer 1

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