How is a JavaScript hash map implemented

Question

I'm using OpenLayers right now and need to draw a tonne of data into a vector layer (greater than 100000 vectors).

To evaluate the efficiency, I'm currently attempting to incorporate all of these vectors into a JavaScript hash map.

I'm curious as to how the JavaScript hash map is implemented—is it a true hash function, or is it just a wrapped function that makes use of a straightforward data structure and a search algorithm?

Answer 1

Because every javascript object is a basic hashmap that accepts a string or a Symbol as its key, your code may look like this:

var map = {};
// add a item
map[key1] = value1;
// or remove it
delete map[key1];
// or determine whether a key exists
key1 in map;

The javascript object is a true hashmap in its implementation, therefore the search complexity is O(1), but there is no separate hashcode() method for javascript strings; instead, the javascript engine implements it internally (V8, SpiderMonkey, JScript.dll, etc...)