Maplike cheat sheet

by jib1

HTML

<div id="div"></div>

JavaScript

var console = {log: s => div.innerHTML += s +"<br>"};

var m = new Map([["a", 1], ["b", 2], ["c", 3]]);
var m2 = new Map(m);
m2.set("c", 4);

console.log(m.get("a"));
m.forEach((e, key) => console.log(key +'='+ e));
console.log([...m]);
console.log([...m.keys()]);
console.log([...m.values()]);
console.log([...m.entries()]);
for (const key of m.keys()) console.log(key);
for (const value of m.values()) console.log(value);
for (const [key, value] of m.entries()) console.log(key +"="+ value);
for (const [key, value] of m) console.log(key +"="+ value);
console.log(m[Symbol.iterator]().next().value);
console.log(m.values().next().value);
console.log(JSON.stringify(m));
console.log(JSON.stringify([...m.entries()].reduce((m, e) => (m[e[0]] = e[1], m), {})));

console.log(JSON.stringify([...m.entries()]));
console.log(JSON.stringify([...m2.entries()]));