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JavaScript Introduction to Programming Objects and Arrays Arrays

Posted by Cesar Marroquin
Cesar Marroquin
10,520 Points

Can you declare an array of unknown size in Javascript?

Can this be done? Will it expand as it gets filled up with elements, or would you just have to create a very large array that would be more than enough size for any data you might want.

3 Answers

Myroslav Tkachenko
Myroslav Tkachenko
10,581 Points
Myroslav Tkachenko
Myroslav Tkachenko
10,581 Points

Yes. Simply create an empty array:

var a = [];

or

var a = new Array();

Then you can add more elements dynamically by specifying any index (your array can even have "gaps" in it, an 'undefined' elements):

a[0] = "first";
a[2] = "third";

or simply add an element to the end of the array:

a[0] = "first";
a[a.length] = "next element";

The elements in an array may not be of the same type. As you can see, arrays in JavaScript are very flexible, so be careful with this flexibility :) There are a handful of methods to manipulate arrays like .pop(), .push(), .shift(), .unshift() etc.

Cesar Marroquin
Cesar Marroquin
10,520 Points
Cesar Marroquin
Cesar Marroquin
10,520 Points

Thank you so much that was very helpful:)!

Davide Pugliese
Davide Pugliese
4,091 Points
Davide Pugliese
Davide Pugliese
4,091 Points

I think this in Java, that did not include this at the beginning like Javascript, is called an array list. Normally, you want to push this a step forward and create your own structures which are: stack, queue. http://www.i-programmer.info/programming/javascript/1674-javascript-data-structures-stacks-queues-and-deques.html http://en.wikibooks.org/wiki/Data_Structures/Stacks_and_Queues