Converting Object to Array using ES6 features

Given a javascript object, how can I convert it to an array in ECMAScript-6 ?

For example, given:

 var inputObj = {a:'foo', b:[1,2,3], c:null, z:55};

The expected output would be:

 ['foo', [1,2,3], null, 55]

The order of the elements in the result is not important to me.

Solution 1:

Use (ES5) Array::map over the keys with an arrow function (for short syntax only, not functionality):

let arr = Object.keys(obj).map((k) => obj[k])

True ES6 style would be to write a generator, and convert that iterable into an array:

function* values(obj) {
    for (let prop of Object.keys(obj)) // own properties, you might use
                                       // for (let prop in obj)
        yield obj[prop];
}
let arr = Array.from(values(obj));

Regrettably, no object iterator has made it into the ES6 natives.

Solution 2:

just use Object.values

Object.values(inputObj); // => ['foo', [1,2,3], null, 55]

Solution 3:

I like the old school way:

var i=0, arr=[];
for (var ob in inputObj)
  arr[i++]=ob;

Old school wins the jsperf test by a large margin, if not the upvotes. Sometimes new additions are "mis-features."

Solution 4:

This can be achieved using the Array Comprehension syntax:

[for (key of Object.keys(inputObj)) inputObj[key]]

Usage example:

var inputObj = {a:'foo', b:[1,2,3], c:null, z:55};
var arr = [for (key of Object.keys(inputObj)) inputObj[key]];
console.log(arr);

// prints [ 'foo', [ 1, 2, 3 ], null, 55 ]