How to get index of the max value in array of objects?

Question

I've got an array with following format:

var dataset = [{
    date: '1',
    value: '55'
}, {
    date: '2',
    value: '52'
}, {
    date: '3',
    value: '47'
}];

And I'm getting the maximum value in it by:

var maxValue = Math.max.apply(Math, dataset.map(function(o) {
    return o.value;
}));

It works very well, there's nothing to worry about. But how I can obtain an index of the maxValue?

I've tried indexOf() (which returns me -1 all the time), jQuery inArray() as well as reduce() but none of them work properly.

I guess there's a more cleaner way by iterating all elements to get the index.

Thanks in advance.

What is the expected result? 0 (55 is the first element) or 1 (55 corresponds to date = 1)? — Salman Arshad
– Salman Arshad, Commented Jul 29, 2015 at 9:16

Salman Arshad · Accepted Answer · 2016-07-21 10:36:20Z

3

As an alternative with Array.forEach

var dataset = [{date:'1',value:'55'},{date:'2',value:'56'},{date:'3',value:'47'}],
    max = -Infinity,
    key;  

dataset.forEach(function (v, k) { 
    if (max < +v.value) { 
        max = +v.value; 
        key = k; 
    }
});

console.log(key);
console.log(dataset[key]);

edited Jul 21, 2016 at 10:36

Salman Arshad

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answered Jul 29, 2015 at 8:35

meze

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1 Comment

Rafal Over a year ago

Hey, it seems to work! Thank you, it's very helpful!

Arun P Johny · Accepted Answer · 2015-07-29 08:11:13Z

2

You can use the temp array created by Array.mp() to find the index like

var dataset = [{
  date: '1',
  value: '55'
}, {
  date: '2',
  value: '59'
}, {
  date: '3',
  value: '47'
}];

var tmp = dataset.map(function(o) {
  return o.value;
});
var maxValue = Math.max.apply(Math, tmp);
//find the index using the tmp array, need to convert maxValue to a string since value is of type string
var index = tmp.indexOf(maxValue + '');

snippet.log(maxValue + ' : ' + index)

<!-- Provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>

answered Jul 29, 2015 at 8:11

Arun P Johny

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5 Comments

Rafal Over a year ago

Thanks. This is more likely what I was doing, when I'm trying this one - it still returning index -1.

Arun P Johny Over a year ago

@Bohdan did you use tmp.indexOf(maxValue + ''); or just tmp.indexOf(maxValue);

Sudharsan S Over a year ago

@Bohdan - Go up with Arun way

Rafal Over a year ago

I did it. The max value is doing fine and it's correct but index is still -1.

Rafal Over a year ago

Unfortunately, even though your solution seems to be correct and it works in fiddle, it doesnt work in my case (I tried to recreate my issue but it's alright when testing in fiddle).

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