How do I select a key/value pair by finding the smallest value in a number of key/value pairs in a JavaScript object?

Question

I have an object that looks like this:

var obj = {
  thingA: 5,
  thingB: 10,
  thingC: 15
}

I would like to be able to select the key/value pair thingA: 5 based on the fact that 5 is the smallest value compared to the other key/value pairs.

Loop through the keys, and compare the values (keep track of the lowest value)? — Rob W
– Rob W, Commented Jul 29, 2012 at 22:35
What about the case where different "keys" have the same smallest value? Let's say thingD : 5 for instance. Is it possible? In that case, what should be the expected result? — ZER0
– ZER0, Commented Jul 29, 2012 at 22:51
@ZER0 Good question! In this case it doesn't matter; any result key will do if it has the smallest value. — Stanislav Beremski
– Stanislav Beremski, Commented Jul 30, 2012 at 8:09

Ry- · Accepted Answer · 2012-07-30 13:25:13Z

2

Nothing built-in does that, but:

var minPair = Object.keys(obj).map(function(k) {
    return [k, obj[k]];
}).reduce(function(a, b) {
    return b[1] < a[1] ? b : a;
});

minPair // ['thingA', 5]

Or, sans ECMAScript 5 extensions:

var minKey, minValue;

for(var x in obj) {
    if(obj.hasOwnProperty(x)) {
        if(!minKey || obj[x] < minValue) {
            minValue = obj[x];
            minKey = x;
        }
    }
}

[minKey, minValue] // ['thingA', 5]

edited Jul 30, 2012 at 13:25

answered Jul 29, 2012 at 22:36

Ry-♦

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1 Comment

Stanislav Beremski Over a year ago

Thanks! I have never really used the map.reduce pattern before so I am going to take some time to learn it.

spaceman12 · Accepted Answer · 2012-07-30 08:00:43Z

1

here is a simple function that can do exactly what you wanted -

function getSmallest(obj)
{
    var min,key;
    for(var k in obj)
    {
        if(typeof(min)=='undefined')
        {
            min=obj[k];
            key=k;
            continue;
        }
        if(obj[k]<min)
        {
            min=obj[k]; 
            key=k;
        }
    }
    return key+':'+min;
}



//test run
var obj={thingA:5,thingB:10,thingC:15};
var smallest=getSmallest(obj)//thingA:5

edited Jul 30, 2012 at 8:00

answered Jul 29, 2012 at 23:35

spaceman12

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