CODEWITHSUNDEEP
javascriptarrays
Muhammad Umer
Muhammad Umer

Reputation: 18097

Convert object keys into array list?

If I have an object like:

var o = {a:1,b:2,c:3};

I want to get:

['a','b','c'];

I want to use for (var i in o) because this will include properties from prototype chain. I could have used Object.keys(o) if I didn't need properties from prototype chain.

I was thinking I could use some of Array.prototype.* methods here. Like map but this is too advance for me.

I can make a string from loop and do split. But is there more efficient and professional level of doing this?

Upvotes: 3

Views: 2232

Answers (3)

Pete
Pete

Reputation: 3254

This is a solution that avoids the for...in that you mentioned. However, I think the for...in solution is much more elegant.

This will walk the prototype chain and return all properties as a recursive function. As well as remove all duplicates.

function getKeys(obj) {
    var keys = Object.keys(obj);
    var parent = Object.getPrototypeOf(obj);
    if (!parent) {
        return keys;
    }
    return keys.concat(getKeys(parent))
               .filter(function (item, index, col) {
                   return col.indexOf(item) === index;
               });
}

var a = { a: 1, b: 2 };
var b = Object.create(a);
b.a = 2;
b.c = 3;
var c = Object.create(b);
console.log(getKeys(c));

Upvotes: 0

Prathik Rajendran M
Prathik Rajendran M

Reputation: 1162

You can use the keys method in lodash, https://lodash.com/docs#keys

You could also use the following code

var arr = [];
var o = {a:1,b:2}
for(k in o) { arr.push(k); }

Here is another version which goes deep into the object

function getKeys(o) { var arr = []; for(k in o) { arr.push(k); if(typeof(o[k]) === 'object') { arr.push(getKeys(o[k])); }} return arr; }

If you have an object like {a:1,b:2, c: {d:1, e:2}} you would get the return as ['a','b','c',['d','e']]

A completely flat version would be this one

function getKeys(o) { var arr = []; for(k in o) { arr.push(k); if(typeof(o[k]) === 'object') { for(j of getKeys(o[k])){ arr.push(j); } }} return arr; }

Upvotes: 4

Darkmouse
Darkmouse

Reputation: 1939

If you have the following hash

var o = {a:1,b:2,c:3};

Create a new empty array for storing the keys

var array_keys = new Array();

Then use a for loop to push the keys into the array

for (var key in o) {
    array_keys.push(key);
}

You can then run alert(array_keys)

Upvotes: 0

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