Javascript algorithm to find elements in array that are not in another array

Late answer with the new ECMA5 javascript:

var x = ["a","b","c","t"];
var y = ["d","a","t","e","g"];

myArray = y.filter( function( el ) {
  return x.indexOf( el ) < 0;
});

var z = $.grep(y, function(el){return $.inArray(el, x) == -1});

Also, that method name is too short for its own good. I would expect it to mean isElementInArray, not indexOf.

For a demo with objects, see http://jsfiddle.net/xBDz3/6/

in ES6 simply

const a1 = ["a", "b", "c", "t"];
const a2 = ["d", "a", "t", "e", "g"];

console.log( a2.filter(x => !a1.includes(x)) );

(another option is a2.filter(x => a1.indexOf(x)===-1) )

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