How to calculate sum of object keys in array - javascript

Question

Question

I am working with firebase and react native.

I have returned an array from my firebase database that looks like this.

[Object, Object,         


        

Answer 1

Either a simple loop

var a = [{level:1},{level:2},{level:3},{level:4}],
        total = 0;
    for (var i=0; i

or reduce

var a = [{level:1},{level:2},{level:3},{level:4}]
console.log(a.reduce( function(cnt,o){ return cnt + o.level; }, 0))