What are useful JavaScript methods that extends built-in objects? [closed]

Question

String Replace All :

String.prototype.replaceAll = function(search, replace)
{
    //if replace is not sent, return original string otherwise it will
    //replace search string with 'undefined'.
    if (replace === undefined) {
        return this.toString();
    }

    return this.replace(new RegExp('[' + search + ']', 'g'), replace);
};

var str = 'ABCADRAE';
alert(str.replaceAll('A','X')); // output : XBCXDRXE

Here's another implementation of String.replaceAll() method

String.prototype.replaceAll = function(search, replace) {
    if (replace === undefined) {
        return this.toString();
    }
    return this.split(search).join(replace);
}

The difference between this one and solution posted here is that this implementation handles correctly regexp special characters in strings as well as allows for word matching

Array.prototype.indexOf = Array.prototype.indexOf || function (item) {
    for (var i=0; i < this.length; i++) {
        if(this[i] === item) return i;
    }
    return -1;
};

Usage:

var list = ["my", "array", "contents"];
alert(list.indexOf("contents"));     // outputs 2

There are a ton of String.prototype functions from James Padolsey

https://github.com/padolsey/string.prototype

These include:

• camelize
• contains
• count
• enclose
• extract
• forEach
• forEachWord
• linkify
• many
• randomize
• remove
• reverse
• shorten
• sort
• toDOM
• trim
• wrap

String.format

String.prototype.format = function (values) {

    var regex = /\{([\w-]+)(?:\:([\w\.]*)(?:\((.*?)?\))?)?\}/g;

    var getValue = function (key) {
            if (values == null || typeof values === 'undefined') return null;

            var value = values[key];
            var type = typeof value;

            return type === 'string' || type === 'number' ? value : null;
        };

    return this.replace(regex, function (match) {
        //match will look like {sample-match}
        //key will be 'sample-match';
        var key = match.substr(1, match.length - 2);

        var value = getValue(key);

        return value != null ? value : match;
    });
};

Usage:

alert('Program: {key1} {key2}'.format({ 'key1' : 'Hello', 'key2' : 'World' })); //alerts Program: hello world

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

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

// left and right trim
String.prototype.trim = function () {
    return this.ltrim().rtrim();
}