JS: Map

Resource

Create new Map

var myMap = new Map([iterable])

iterable: Array or other iterable object are key-value pair;

Properties

myMap.size: Return the number of elements;

Methods

myMap.clear(): Remove all key/value pairs;
myMap.delete(key): Return true if the key value exist in Map and has been removed;
myMap.entries(): Return a new Iterator object that contains an array of [key, value] in insertion order;
myMap.forEach(callbackFunction):

function callbackFunction(value, key, map) {
  console.log(`m[${key}] = ${value}`);
}

myMap.get(key): Return value of the key or undefined ;
myMap.has(key): Return boolean ;
myMap.keys(): Return Iterator object contains keys ;
myMap.set(key, value): Set key and value, Return Map object;
myMap.values: Return Iterator object contains values ;
myMap[Symbol.iterator] (): Same like myMap.entries() ;

const mapIter = myMap[Symbol.iterator]();
console.log(mapIter.next().value);