#code #javascript

The correct way to add values to a Map in JavaScript is with the map.set(key, value) function. Using the map[key]=value notation seems to work at first, but the key-value pair is ignored by methods on the Map, like map.has(key) and map.delete(keys).

Maps and Objects are not the same thing. They are similar In the fact that they are both key-value pairs. But there are notable differences : - an Object contains values by default (prototype) - an Object is vulnerable to object injection attacks, so a Map is safer - any value can be used as key in a Map. For Objects, only String and Symbols are allowed - Map is iterable and the keys are ordered in the order they were created - Map has a size property - Map has better performances when adding & removing many keys

Map was added with ES6 (2015) and is not supported by all browsers.