Some Essential JavaScript Prototype Functions to Enhance your JavaScript Applications

// -- Standard functions
// String.contains() - See if a string contains a string
String.prototype.contains = function(str) {
    return (this.indexOf(str) != -1);
};

// String.getChar() - Gets the character at a specific position
String.prototype.getChar = function(char_pos) {
    return this.substring(char_pos, char_pos + 1);
}

// String.trim() - Strips spaces from beginning and end of string
String.prototype.trim = function() {
    return this.replace(/^\s+|\s+$/g, '');
};

// Array.contains() - See if an array contains an object
if (typeof Array.prototype.contains === 'undefined') {
    Array.prototype.contains = function(obj) {
        var i = this.length;
        while (i--) {
            if (this[i] === obj) {
                return true;
            }
        }
        return false;
    };
}

// Array.copy() - Copy an array
if (typeof Array.prototype.copy === 'undefined') {
    Array.prototype.copy = function() {
        var a = [],
            i = this.length;
        while (i--) {
            a[i] = typeof this[i].copy !== 'undefined' ? this[i].copy() : this[i];
        }
        return a;
    };
}

// Array.forEach( function ) - Apply a function to each element
Array.prototype.forEach = function(f) {
    var i = this.length,
        j, l = this.length;
    for (i = 0; i < l; i++) {
        if ((j = this[i])) {
            f(j);
        }
    }
};

// Array.indexOf( value, begin, strict ) - Return index of the first element that matches value
Array.prototype.indexOf = function(v, b, s) {
    for (var i = +b || 0, l = this.length; i < l; i++) {
        if (this[i] === v || s && this[i] == v) {
            return i;
        }
    }
    return -1;
};

// Array.insert( index, value ) - Insert value at index, without overwriting existing keys
Array.prototype.insert = function(i, v) {
    if (i >= 0) {
        var a = this.slice(),
            b = a.splice(i);
        a[i] = v;
        return a.concat(b);
    }
};

// Array.lastIndexOf( value, begin, strict ) - Return index of the last element that matches value
Array.prototype.lastIndexOf = function(v, b, s) {
    b = +b || 0;
    var i = this.length;
    while (i-- > b) {
        if (this[i] === v || s && this[i] == v) {
            return i;
        }
    }
    return -1;
};

// Array.random( range ) - Return a random element, optionally up to or from range
Array.prototype.random = function(r) {
    var i = 0,
        l = this.length;
    if (!r) {
        r = this.length;
    }
    else if (r > 0) {
        r = r % l;
    }
    else {
        i = r;
        r = l + r % l;
    }
    return this[Math.floor(r * Math.random() - i)];
};

// Array.shuffle( deep ) - Randomly interchange elements
Array.prototype.shuffle = function(b) {
    var i = this.length,
        j, t;
    while (i) {
        j = Math.floor((i--) * Math.random());
        t = b && typeof this[i].shuffle !== 'undefined' ? this[i].shuffle() : this[i];
        this[i] = this[j];
        this[j] = t;
    }
    return this;
};

// Array.unique( strict ) - Remove duplicate values
Array.prototype.unique = function(b) {
    var a = [],
        i, l = this.length;
    for (i = 0; i < l; i++) {
        if (a.indexOf(this[i], 0, b) < 0) {
            a.push(this[i]);
        }
    }
    return a;
};

// Array.walk() - Change each value according to a callback function
Array.prototype.walk = function(f) {
    var a = [],
        i = this.length;
    while (i--) {
        a.push(f(this[i]));
    }
    return a.reverse();
};