Array of objects intersection

Question

I have two lists of objects and I would like to filter my array1 without the file key that are in the array2 :

What I did :

array1 = array1.filter(function(n) {
    for(var i=0; i < array2.length; i++){
      if(n.file != array2[i].file){
        return n;
      }
    }
});

This returns exactly the array1 whereas if I replace != with == it returns the objects I want to get rid of.

I don't understand why.

https://jsfiddle.net/hrzzohnL/1/

So at the end I would like to end with this array :

[
    {
     "file": "tttt.csv",
     "media": "tttt"
    }
]

Answer 1

Using filter and some functions

var array1 = [{ "file": "tttt.csv", "media": "tttt" }, { "file": "bob_bob.csv", "media": "bob_bob" }, { "file": "bob1_bob1.csv", "media": "bob1_bob1" }, ];

var array2 = [{ "title": "bob_bob", "version": "bob", "date": "27/4/2016", "selected": false, "file": "bob_bob.csv", "media": "bob_bob", "exists": true }, { "title": "bob1_bob1", "version": "bob", "date": "27/4/2016", "selected": false, "file": "bob1_bob1.csv", "media": "bob_bob", "exists": true }]

var res = array1.filter(n => !array2.some(n2 => n.file == n2.file));

document.write(JSON.stringify(res));

^{*solution uses ES6 arrow function, it may not work in old browsers}