Extract values from a list of objects in javascript using underscore

Question

I have a list of objects, where each object has numerical values:

var cpuInfo = [
  { user: 189625143,
    nice: 0,
    sys: 40239022,
    idle: 2087123838,
    irq: 720490 },
  { user: 76627160,
    nice: 0,
    sys: 35444113,
    idle: 2204916386,
    irq: 18233303 }
]

I need to calculate the value of idle divided by the sum of all values.

For that, I need to get the sum of all of the values in all of the objects.

I've tried doing this to extract just the values:

_(cpuInfo).each(_.values)

I expected it to return a list like so:

[189625143, 0, 40239022, 2087123838, 720490, 76627160, 0, 35444113, 2204916386, 18233303]

But for some reason it returns the exact same thing I started out with - a list of objects. Even if I expand it to this:

_(cpuInfo).each(function(item) { return _(item).values() })

It still returns just the list of objects.

What am I doing wrong?

Oleksandr T. · Accepted Answer · 2014-11-30 09:51:51Z

4

var res = _.map(cpuInfo, function (el) {
  return _.values(el)  
})
res = _.flatten(res)

console.log(res);

Demo: http://jsbin.com/rodipu/1/edit?js,console

answered Nov 30, 2014 at 9:51

Oleksandr T.

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Comments

code-jaff · Accepted Answer · 2014-11-30 10:22:56Z

2

In pure JavaScript

temp = [];
cpuInfo.forEach(function(obj){
    Object.keys(obj).forEach(function(k){
        temp.push(obj[k]);
    });
});

Ref - Object.keys(), Array.prototype.forEach()

Note - both functions compatible with >IE8

answered Nov 30, 2014 at 10:22

code-jaff

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