I'm a bit more familiar with python, so what is the javascript equivalent of:

In [25]: listA = [1,2,3,4,5,1,1]
In [26]: listB = [1,2]
In [27]: intersect = [element for element in listA if element in listB]
In [28]: intersect

Out[28]: [1, 2, 1, 1]

This is the closest I can get:

var arrA = [1,1,3,4,5,5,6];
var arrB = [1,5];
var arrC = [];
$.each(arrA, function(i,d){ if (arrB.indexOf(d)> -1){arrC.push(d);} ;});

Any ments on preferred methods? I saw this answer, but it was not exactly what I wanted to answer.

I'm a bit more familiar with python, so what is the javascript equivalent of:

In [25]: listA = [1,2,3,4,5,1,1]
In [26]: listB = [1,2]
In [27]: intersect = [element for element in listA if element in listB]
In [28]: intersect

Out[28]: [1, 2, 1, 1]

This is the closest I can get:

var arrA = [1,1,3,4,5,5,6];
var arrB = [1,5];
var arrC = [];
$.each(arrA, function(i,d){ if (arrB.indexOf(d)> -1){arrC.push(d);} ;});

Any ments on preferred methods? I saw this answer, but it was not exactly what I wanted to answer.

• javascript
• jquery

• 1 this one does seem to work, so what the question is? – Igor Dymov Commented Mar 11, 2013 at 7:23
• I'm new to javascript, just thought I'd see what people have to say. – gus Commented Mar 11, 2013 at 7:35
• If it works and you want to know whether there's something better, you're better off at codereview.stackexchange.. Also, this isn't "pure" JavaScript ($.each is from the jQuery library). If you're new to JavaScript don't use jQuery at first. First get used to the language and see what isn't possible in JavaScript, then start to use a library to get rid of the limitations. – Zeta Commented Mar 11, 2013 at 7:39

1 Answer 1

You could use Array.filter like this:

var aa = [1,2,3,4,5,1,1]
   ,ab = [1,2]
   ,ac = aa.filter(function(a){return ~this.indexOf(a);},ab);
//=> ac is now [1,2,1,1]

Or as extension for Array.prototype

Array.prototype.intersect = function(arr){
 return this.filter(function(a){return ~this.indexOf(a);},arr);
}
// usage
[1,2,3,4,5,1,1].intersect([1,2]); //=> [1,2,1,1]

See MDN for the Array.filter method (also contains a shim for older browsers)