Array.prototype method with 'undefined' Output in Javascript
Question
I don't understand why is the output is 'undefined'?
JSON.stringify(a.maxKey())
The output is still the same even if it is used like in the above.
Array.prototype.maxKey = function (){ Math.max.apply(Math, this.map( function(item){ return item.key} ) ) } var a = [{key:1}, {key:2}] alert(a.maxKey())
1 answers
solution1
0 2017-03-29 22:01:46
You miss return keyword.
Array.prototype.maxKey = function() { return Math.max.apply(Math, this.map(item => item.key)); } var a = [{ key: 1}, { key: 2}]; console.log(a.maxKey())
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