javascriptdictionaryjavascript-objectses6-map

Is there any advantage to using Object.create(null) over a Map?

I've seen people use code that looks like

const STUFF_MAP = Object.create(null);

STUFF_MAP would like suggested only be used like a map, so I understand why using Object.create(null) is better than {} (removing the properties that could cause conflicts etc.), but is there any advantage to not just use

const STUFF_MAP = new Map();

When would I use each one? Does it have to do with being compiled to pre es6?

Solution

  • Does it have to do with being compiled to pre es6?

    Yes, Object.create(null) is ES5 and won't need a polyfill for Map, if you need to support old browsers.

    Apart from that, you should prefer the more modern Map which is also clearly indicates the purpose of a variable. You will need to access the collection using has/get/set methods, not in operator/bracket syntax/assignment. This can sometimes lead to code that isn't as concise, e.g. for incrementing a value you cannot use a compound assignment operator.

    As for performance, there should not be much of a difference; if you care, do a benchmark for your particular situation.