17. Create a simple store for DOM element

easy  - accepted / - tried

We have Map in es6, so we could use any data as key, such as DOM element.

const map = new Map()
map.set(domNode, somedata)

What if we need to support old JavaScript env like es5, how would you create your own Node Store as above?

You are asked to implement a Node Store, which supports DOM element as key.

class NodeStore {

  set(node, value) {

  get(node) {

  has(node) {



Map is disabled when judging your code, it is against the goal of practicing.

You can create a simple general Map polyfill. Or since you are asked to support specially for DOM element, what is special about DOM element?

What is the Time / Space cost of your solution?

Think aloud!