add key value pair of objects in an array

Question

function Person (name, age) {
  this.name = name;
  this.age = age;
}

var family = []

var people = {alice:40, bob:42, michelle:8, timmy:6};


for (var key in people) {
  family.push({key:people[key]})
}

console.log(family);

This is not giving me the keys. its giving 'key' for each key. what is the proper way to add {key:value} pair of objects in an array?

UPDATE Based on K3N solution below, this is what i understood works best if we are declaring from a constructor each time:

keys = Object.keys(people);
for (var i = 0; i < keys.length; i++) {
  family.push(new Person(keys[i], people[keys[i]]));
}

who ever down votes, specify your reason so i can add whatever info you are looking for — user2290820
– user2290820, Commented Jun 14, 2015 at 9:46
Note that for-in loops are considerable slower than a normal for-loop. — user1693593
– user1693593, Commented Jun 14, 2015 at 10:08
@K3N thanks, that will be further optimization. will make sure. the answer to this problem was to fix the output which i wasn't getting at first — user2290820
– user2290820, Commented Jun 14, 2015 at 10:10
@user2290820 the approach you have used seems closer to K3N instead of mine as you have not used square notation instead passed the key as argument to constructor, so i think you should not accept mine answer — bugwheels94
– bugwheels94, Commented Jun 14, 2015 at 10:12

score 3 · Accepted Answer · 2015-06-14 10:09:07Z

3

Since your people arrays contains name of the person as key, and value being the age (be careful as if you get two persons with the same name nuclear reaction in time-space happens...!).

You can do it like this:

function Person (name, age) {
  this.name = name;
  this.age = age;
}

var family = []

var people = {alice:40, bob:42, michelle:8, timmy:6};

var keys = Object.keys(people);               // list all (ownProperty) keys in object
for(var i = 0, key; key = keys[i]; i++) {     // loop through
  family.push(new Person(key, people[key]));  // push it
}

document.write(JSON.stringify(family));       // demo output

edited Jun 14, 2015 at 10:09

answered Jun 14, 2015 at 9:57

user1693593

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1 Comment

user2290820 Over a year ago

@torox it is as well as the the other one. i selected this one first. the other one is elegant. but the changes like family.push(new Person(key, people[key])); were made later. anyhow i wasnt looking to optimize.

bugwheels94 · Accepted Answer · 2015-06-21 20:30:42Z

2

Wither use Bracket notation so that key can be treated as a variable property name

for (var key in people) {
    var temp={};
    temp[key]=people[key]
    family.push(temp)
}

Or Computed property name

for (var key in people) {
  family.push({[key]:people[key]})
}

edited Jun 21, 2015 at 20:30

answered Jun 14, 2015 at 9:55

bugwheels94

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2 Comments

user2290820 Over a year ago

this is not efficient. i see var created at every iteration

user2290820 Over a year ago

This is better. so you include the key ina bracket. why does that work?

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