javascript insert([index],[string]) method (String.prototype.insert)

String.prototype.insert.js

// String insert method
String.prototype.insert = function (index, string) {
    if (index > 0) {
      // necessary fix
      if (string.charCodeAt(0) == 13){
	    string = "\n";
    	}
        var ret = this.substring(0, index) + string + this.substring(index, this.length);
        return ret;
    } else if (index == this.length) {
        return this + string;
    } else {
        return string + this;
    }
};