How to declare Javascript array with numeric keys (like php does)?

Question

What I do in php:

$arr = [1=>'a', 3=>'b', 2017=>'zzzzZZZZ'];

What I konw in js:

var arr = [];
arr[1] = 'a';
arr[3] = 'b';
arr[2017] = 'zzzzZZZZ';

• Yang Yu: not sure what your question is?

Answer 1

Your code would make an array of length 2018 since the largest array index defined is 2017 and the remaining undefined elements are treated as undefined.

var arr = [];
arr[1] = 'a';
arr[3] = 'b';
arr[2017] = 'zzzzZZZZ';
console.log(arr.length, arr);

---

In JavaScript, there is no associative array instead there is object for key-value pair of data.

var obj = {
 1 : 'a',
 3 : 'b',
 2017 : 'zzzzZZZZ'
}

var obj = {
 1: 'a',
 3: 'b',
 2017: 'zzzzZZZZ'
}
console.log(obj);

Refer : javascript Associate array

• Rajesh Dixit: I guess you should also include why as well.
• bijiDango: Very odd that I can't use obj.1 to get the value but obj[1] or obj['1']. Seems that JS object stores data as array, and the most basic way to fetch data is also array. In the meanwhile, array act like restricted object.
• Pranav C Balan: @bijiDango : that's because the property name starts with a name so you can't use dot notation ...... check the docs : developer.mozilla.org/en/docs/Web/JavaScript/Reference/…