How to get a list of key values from array of JavaScript objects

Question

Lets say, I have an array of objects like this:

var students = [{
    name: 'Nick',
    achievements: 158,
    points: 14730
}, {
    name: 'Jordan',
    achievements: '175',
    points: '16375'
}, {
    name: 'Ramon',
    achievements: '55',
    points: '2025'
}];

How do I loop through it (if i have to) so I get a list of certain key values. Lets say a list of all names.

Thanks.

Answer 1

You can take Array.map(). This method returns an array with the elements from the callback returned. It expect that all elements return something. If not set, undefined will be returned.

var students = [{
    name: 'Nick',
    achievements: 158,
    points: 14730
}, {
    name: 'Jordan',
    achievements: '175',
    points: '16375'
}, {
    name: 'Ramon',
    achievements: '55',
    points: '2025'
}];
var nameArray = students.map(function (el) { return el.name; });
document.getElementById('out').innerHTML = JSON.stringify(nameArray, null, 4);

<pre id="out"></pre>

Answer 2

Using forEach:

var a = [];
students.forEach(function(obj){
    a.push(obj.name);
})
console.log(a);

Output:

 ["Nick", "Jordan", "Ramon"]