Find if Array contains a user

Question

I have a parse background job that contains a simple query.each for one class. This class has 2 Arrays field filled with objects.IDs. Inside this query, for every single object, i need to check if the objects.ID of the first Array are contained in the second Array. Basically in a simple loop:

    var j = 0;
    for (var j = 0; j < firstArray.length; j++) {
        if(firstArray[j] "isContainedIn" secondArray){
        // my custom code
        }
    }

What i can't figure out is the function to use, if exist..Does javascript have a function like that or i need to make a nested loop to achieve my goal?

EDIT: i worked it out using indexOf but the solution proposed by Shqiptar didn't work so here is the one that actually works:

first Array name = usersEligibleToVote second Array name = usersThatVoted

for (var j = 0; j < usersEligibleToVote.length; j++) {
        if(usersThatVoted.indexOf(usersEligibleToVote[j]) === -1){
            console.log("user.id "+usersEligibleToVote[j]+" needs to vote");
        } else {
            console.log("user.id "+usersEligibleToVote[j]+" has voted");
        }
}

Nested loop unless the pointers are pointing to the same object... — brso05, Nov 11 '14 at 18:58
You can use indexOf if they are the exact same object not value wise but pointers to the same object — brso05, Nov 11 '14 at 19:00
Duplicate of http://stackoverflow.com/questions/237104/array-containsobj-in-javascript — Mike Grabowski, Nov 11 '14 at 19:13
I saw that question but my answer is about cloud-code and i don't think every javascript function is available in it.. — Diego, Nov 11 '14 at 19:20

Shqiptar_Programmer · Answer 1 · 2014-11-11T19:13:53.987

1

var j = 0;
    for (var j = 0; j < firstArray.length; j++) {
        if(firstArray[j].contains(secondArray))
        {
        // your custom code here
        }
    }

And then for checking if an object is the same :

var j = 0;
    for (var j = 0; j < firstArray.length; j++) {
        if(firstArray[j].indexOf(secondArray) != -1) 
        {
        // your custom code here
        }
    }

edited Nov 11 '14 at 19:13

answered Nov 11 '14 at 19:01

Shqiptar_Programmer

487
4
13

1

Caution: It must be the same object not an object with the same values. – brso05 Nov 11 '14 at 19:02
I think you want `secondArray.contains(firstArray[j])` – Colin DeClue Nov 11 '14 at 19:03
1

`firstArray[j].indexOf(secondArray)` you want to do ` != -1` here. A return value of 0 (falsy) means it is in the array. And you have your conditions all backwards. – Colin DeClue Nov 11 '14 at 19:08
`Array.prototype.contains` is not yet implemented. -1 for that and for bad indexOf check as well. – Mike Grabowski Nov 11 '14 at 19:15
care to make any edits in this code other then just criticising me? – Shqiptar_Programmer Nov 12 '14 at 07:32

score 0 · Answer 2 · answered Nov 11 '14 at 19:04

0

I would process it through a simple jQuery and javascript for loop like so:

var arr1;
var arr2;
var i;
for(i = 0; i < arr1.length; i++) {
    if ($.inArray(arr1[i], arr2) {
        break; //do things here or what not
        }
}

answered Nov 11 '14 at 19:04

dhershman

341
2
12

You will be down voted for suggesting jQuery "for such a simple thing" hehe. Assuming that one currently uses it - than it's fair. – Mike Grabowski Nov 11 '14 at 19:11
No down votes :( It's technically only two lines :P It's much quicker for me to use jQuery inArray I use it for several product compares when going through product lists and promotions to grab them. – dhershman Nov 11 '14 at 19:13
Yep, the only thing is that some users may want to bundle the whole jQuery just to use this helper which is stupid as it's not the purpose of that plugin. For javascript logic operations and stuff -> checkout lodash or underscore. – Mike Grabowski Nov 11 '14 at 19:16

Find if Array contains a user

2 Answers2