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up vote 183 down vote favorite
30

I have a javascript array dataArray which I want to push into a new array newArray. Except I don't want newArray[0] to be dataArray. I want to push in all the values into the new array:

var newArray = [];

newArray.pushValues(dataArray1);
newArray.pushValues(dataArray2);
// ...

or even better:

var newArray = new Array (
   dataArray1.values(),
   dataArray2.values(),
   // ... where values() (or something equivalent) would push the individual values into the array, rather than the array itself
);

So now the new array contains all the values of the individual data arrays. Is there some shorthand like pushValues available so I don't have to iterate over each individual dataArray, adding the values 1 by 1?

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6 Answers 6

up vote 222 down vote accepted

Use the concat function, like so:

var arrayA = [1, 2];
var arrayB = [3, 4];
var newArray = arrayA.concat(arrayB);

The value of newArray will be [1, 2, 3, 4] (arrayA and arrayB remain unchanged; concat creates and returns a new array for the result).

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3  
A better reference would be: developer.mozilla.org/en/JavaScript/Reference/Global_Objects/… [1]: developer.mozilla.org/en/JavaScript/Reference/Global_Objects/… –  Jamund Ferguson Feb 23 '11 at 5:41
28  
Slow though: jsperf.com/concat-vs-push-apply/10 –  w00t Aug 20 '12 at 19:42
    
The answer below is much more detailed, I agree- wish I could assign that as the correct answer. –  WiseGuyEh Feb 22 '13 at 15:38
up vote 292 down vote

Provided your arrays are not huge (see caveat below), you can use the push() method of the array to which you wish to append values. push() can take multiple parameters so you can use its apply() method to pass the array of values to be pushed as a list of function parameters. This has the advantage over using concat() of adding elements to the array in place rather than creating a new array.

However, it seems that for large arrays (of the order of 100,000 members or more), this trick can fail. For such arrays, using a loop is a better approach. See http://stackoverflow.com/a/17368101/96100 for details.

var newArray = [];
newArray.push.apply(newArray, dataArray1);
newArray.push.apply(newArray, dataArray2);

You might want to generalize this into a function:

function pushArray(arr, arr2) {
    arr.push.apply(arr, arr2);
}

... or add it to Array's prototype:

Array.prototype.pushArray = function(arr) {
    this.push.apply(this, arr);
};

var newArray = [];
newArray.pushArray(dataArray1);
newArray.pushArray(dataArray2);

... or emulate the original push() method by allowing multiple parameters using the fact that concat(), like push(), allows multiple parameters:

Array.prototype.pushArray = function() {
    this.push.apply(this, this.concat.apply([], arguments));
};

var newArray = [];
newArray.pushArray(dataArray1, dataArray2);

Here's a loop-based version of the last example, suitable for large arrays and all major browsers, including IE <= 8:

Array.prototype.pushArray = function() {
    var toPush = this.concat.apply([], arguments);
    for (var i = 0, len = toPush.length; i < len; ++i) {
        this.push(toPush[i]);
    }
};
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2  
note: newArray.push.apply(newArray, dataArray1); gives the same as Array.prototype.push.applay(newArray,dataArra1); –  user669677 Jul 5 '13 at 11:02
    
push.apply whas exacly what I was looking for, thx –  Jaak Kütt Nov 9 '13 at 17:09
up vote 10 down vote 
var a=new Array('a','b','c');
var b=new Array('d','e','f');
var d=new Array('x','y','z');
var c=a.concat(b,d)

Does that solve your problem ?

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up vote 0 down vote

Most simple:

var newArray = dataArray1.slice(0);
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This does not cover the problem in the question: concatenating two arrays. –  frasertweedale May 8 at 9:40
up vote -2 down vote

Тhis is a working code and it works fine:

var els = document.getElementsByTagName('input'), i;
var invnum = new Array();
var k = els.length;
for(i = 0; i < k; i++){invnum.push(new Array(els[i].id,els[i].value))}
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up vote -4 down vote

instead of push() function use concat function for IE. example,

var a=a.concat(a,new Array('amin'));
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