# HashMap nodejs p5js
**URL:** https://discourse.processing.org/t/hashmap-nodejs-p5js/1381
**Category:** Beginners
**Created:** [June 30, 2018, 11:10am UTC](https://discourse.processing.org/t/hashmap-nodejs-p5js/1381 "2018-06-30T11:10:43Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@lmccandless](https://discourse.processing.org/u/lmccandless)
#### Post date: [June 30, 2018, 11:10am UTC](https://discourse.processing.org/t/hashmap-nodejs-p5js/1381/1 "2018-06-30T11:10:43Z")
I’m coming from processing to p5js and looking for HashMap functionality.
I’m using node.js and did npm install hashmap
in my test sketch, doing var hm = new HashMap(); inside setup() prevents my sketch from working. Not sure how to go about debugging this as I’m very new to javascript, doing npm list shows hashmap is installed.
nevermind, I guess every array is a hashmap.
how can I get the size of an array when it has string keys? .length doesn’t work. I read to use jquery to get .size() for arrays, i did npm install jquery but get “TypeError: spriteAtlas.size is not a function”
found solution, Object.keys(spriteAtlas).length
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### Author:  [@GoToLoop](https://discourse.processing.org/u/GoToLoop)
#### Post date: [June 30, 2018, 2:11pm UTC](https://discourse.processing.org/t/hashmap-nodejs-p5js/1381/2 "2018-06-30T14:11:47Z")
> [@lmccandless](#):
>
> Never mind. I guess every Array is a HashMap.
Actually, every JS Object functions kinda like a HashMap. 🤓
> [@lmccandless](#):
>
> How can I get the size of an Array when it has String keys?
An Array’s _length_ property only tracks down the quantity of positive integer indices up to 2\*\*32: 🧐
> **[Array: length - JavaScript | MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/length)**
>
> The length data property of an Array instance represents the number of elements in that array. The value is an unsigned, 32-bit integer that is always numerically greater than the highest index in the array.
An invalid index becomes a regular keyed property which is invisible to its _length_ property. 👻
Rather than forcing an Array or an Object to behave like a Java Map, go w/ an actual JS Map container: 🤩
> **[Map - JavaScript | MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map)**
>
> The Map object holds key-value pairs and remembers the original insertion order of the keys.
> Any value (both objects and primitive values) may be used as either a key or a value.
> **[Keyed collections - JavaScript | MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Keyed_collections)**
>
> This chapter introduces collections of data which are indexed by a key; Map and Set objects contain elements which are iterable in the order of insertion.