StartsWith(string suffix,bool ignoreCase), EndsWith(string suffix,bool ignoreCase) and Trim() :

Starts - Ends & Trim.js

// string.StartWith implementation
String.prototype.StartsWith = function(prefix,ignoreCase) {
    if( !prefix ) return false;
    if( prefix.length > this.length ) return false;
    if( ignoreCase ) {
        if( ignoreCase == true ) {
            return (this.substr(0, prefix.length).toUpperCase() == prefix.toUpperCase());
        }
    }
    return (this.substr(0, prefix.length) === prefix);
}

// string.EndsWith implementation
String.prototype.EndsWith = function(suffix,ignoreCase) {
    if( !suffix ) return false;
    if( suffix.length > this.length ) return false;
    if( ignoreCase ) {
        if( ignoreCase == true ) {
            return (this.substr(this.length - suffix.length).toUpperCase() == suffix.toUpperCase());
        }
    }
    return (this.substr(this.length - suffix.length) === suffix);
}

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