Add property to javascript array

Question

Arrays have a \"length\" property by default.

Can I add custom properties to them?

Without having to make them objects

Answer 1

Arrays are objects and therefore you can add your own properties to them:

var arr = [1, 2, 3]; arr.foo = 'bar';

Extending from other answers, here are the following ways of iterating over the array, excluding custom properties.

1) Using a standard for loop

for (let i = 0; i < arr_length; i++)
    console.log(arr[i]);

or if not using ES6:

for (var i = 0; i < arr.length; i++)
    console.log(arr[i]);

2) Using the for ... of loop (ES6+)

for (let el of arr)
    console.log(el)

3) Using Array.prototype.forEach (ES6+)

arr.forEach(el => console.log(el));

or

arr.forEach(function(el) {
    console.log(el);
});

Iterating over the array, including all properties (e.g custom properties, length)

for (let prop in arr)
    console.log(prop);

or if not using ES6:

for (var prop in arr)
    console.log(prop);