Entry

How do you prototype Array to add a function like shift?

Jan 23rd, 2001 03:56
Acebone, acebone, Martin Honnen,

Here is the code
function Array_shift () {
  var el = this[0];
  for (var i = 1; i < this.length; i++)
    this[i - 1] = this[i];
  this.length = this.length - 1;
  return el;
}
if (window.Array && !window.Array.prototype.shift)
  window.Array.prototype.shift = Array_shift;
Example:
var a = [1, 2, 3];
alert(a.shift());
alert(a);
===========================================================
Actually Peter Belesis has made an entire implementation
of the array functions not supported by Internet Exploder.
He has released it under the GNU license so I feel free to 
post the code. Copy/Paste it into a .js file and include it
in your page as you see fit. 
To read an interesting tutorial on arrays by Peter visit:
        http://www.webreference.com/dhtml/column33/
 * -------------------- Code Begin -------------------------------------
--
/* arrayprototype.js
 * by Peter Belesis. v1.0 000516
 * Copyright (c) 2000 Peter Belesis. All Rights Reserved.
 * Originally published and documented at http://www.dhtmlab.com/
 * License to use is granted if and only if this entire copyright notice
 * is included.
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * ---------------------------------------------------------------------
-
 * array_roll function (c) 2001 Esben Maaløe, same licensing terms as 
above.
*/
if(Array.prototype.push && ([0].push(true)==true))Array.prototype.push 
= null;
if(Array.prototype.splice && typeof([0].splice(0))=="number")
Array.prototype.splice = null;
if(!Array.prototype.shift) {
	function array_shift() {
		firstElement = this[0];
		this.reverse();
		this.length = Math.max(this.length-1,0);
		this.reverse();
		return firstElement;
	}
	Array.prototype.shift = array_shift;
}
if(!Array.prototype.unshift) {
	function array_unshift() {
		this.reverse();
		for(var i=arguments.length-1;i>=0;i--){
			this[this.length]=arguments[i]
		}
		this.reverse();
		return this.length
	}
	Array.prototype.unshift = array_unshift;
}
if(!Array.prototype.push) {
	function array_push() {
		for(var i=0;i<arguments.length;i++){
			this[this.length]=arguments[i]
		};
		return this.length;
	}
	Array.prototype.push = array_push;
}
if(!Array.prototype.pop) {
	function array_pop(){
	    lastElement = this[this.length-1];
		this.length = Math.max(this.length-1,0);
	    return lastElement;
	}
	Array.prototype.pop = array_pop;
}
if(!Array.prototype.splice) {
    function array_splice(ind,cnt){
        if(arguments.length == 0) return ind;
        if(typeof ind != "number") ind = 0;
        if(ind < 0) ind = Math.max(0,this.length + ind);
        if(ind > this.length) {
            if(arguments.length > 2) ind = this.length;
            else return [];
        }
        if(arguments.length < 2) cnt = this.length-ind;
        cnt = (typeof cnt == "number") ? Math.max(0,cnt) : 0;
        removeArray = this.slice(ind,ind+cnt);
        endArray = this.slice(ind+cnt);
        this.length = ind;
        for(var i=2;i<arguments.length;i++){
            this[this.length] = arguments[i];
        }
        for(var i=0;i<endArray.length;i++){
            this[this.length] = endArray[i];
        }
        return removeArray;
    }
	Array.prototype.splice = array_splice;
}
if (!window.Array.prototype.roll)
{
	function array_roll (direction) {
		direction = direction || false
		if ( !direction )
		{
			this.splice(this.length, 1, this[0])
			this.splice(0,1)
		} else
		{
			this.splice(0,0, this[this.length-1])
			this.splice(this.length-1,1)
		}
	}
	window.Array.prototype.roll = array_roll; 
}
* -------------------- Code End ----------------------------------------
-