gbland777 gbland777 - 2 months ago 36
React JSX Question

How to calculate sum of object keys in array - javascript

Question



I am working with firebase and react native.

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

[Object, Object, Object]


Under each object I have returned a single item, "level:4".

So I have three objects containing 4,5,6. How do I sum these together?

Thanks!

Answer

Either a simple loop

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

or reduce

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