Using array map to filter results with if conditional

Issue

I am trying to use an array map to filter a object a bit further to prepare it to send to the server to for saving. I can filter to 1 key value, which is great, but I want to take it 1 step further and check them against a boolean inside.

So, right now this is what I have -

$scope.appIds = $scope.applicationsHere.map( function(obj){
        if(obj.selected == true){
            return obj.id;
        }
    });

This works great for pulling out the id's, however I don't want to push them in this new array if they their selected value == false, so I put a conditional to filter further. This somewhat works, I get an array of id's, but the id's that have .selected == false are still in the array, just with the value of null. So If I have 4 items in the object and 2 of them are false it looks like this -

 appIds = {id1, id2, null, null};

My question is - is there a way to do this without the nulls being put in there. Thanks for reading!

Solution

You're looking for the .filter() function:

  $scope.appIds = $scope.applicationsHere.filter(function(obj) {
    return obj.selected;
  });

That'll produce an array that contains only those objects whose "selected" property is true (or truthy).

edit sorry I was getting some coffee and I missed the comments - yes, as jAndy noted in a comment, to filter and then pluck out just the "id" values, it'd be:

  $scope.appIds = $scope.applicationsHere.filter(function(obj) {
    return obj.selected;
  }).map(function(obj) { return obj.id; });

Some functional libraries (like Functional, which in my opinion doesn't get enough love) have a .pluck() function to extract property values from a list of objects, but native JavaScript has a pretty lean set of such tools.

Answered By - Pointy