Strange behavior when add element to array by key [duplicate]

Question

I don't understand why is array so strange when I add element by key. For example:

var test = new Array();
test['a'] = 'aaa';
test['b'] = 'bbb';

test.length == 0; // true. Why?

And when I run:

test.map(function(el){
   console.log(el);
});
// nothing print. Why?

When I add element with push method everything works OK. Thanks

You're adding a property to the object, it doesn't change the length of an array. — pawel
– pawel, Commented Jan 12, 2015 at 16:28

atmd · Accepted Answer · 2015-01-12 16:35:35Z

2

Arrays in javascript are not associative, you can't set keys like that i.e.

var test = [];

test.push('aaa');
test.push('bbb');

// OR

test[0] = 'aaa';
test[1] = 'bbb';

test.length = 2

answered Jan 12, 2015 at 16:29

atmd

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