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How to calculate sum of object keys in array - javascript

rated 0 times [ 44] [ 4] / answers: 1 / hits: 34354 / 8 Years ago, fri, september 9, 2016, 12:00:00

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!

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nathanaelzechariahl

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answered 8 Years ago lucianom · Accepted 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;

    }

console.log('total', total)

or reduce

var a = [{level:1},{level:2},{level:3},{level:4}]

console.log(a.reduce( function(cnt,o){ return cnt + o.level; }, 0))