如果键是对象js，如何从映射中的键获取值

Question

How can I get a key value from a map object if my key value is an object like this example?

const map1 = new Map();
map1.set({x:0,y:0}, 'val');

console.log(map1.get({x:0,y:0}));
//output: undefined

I am creating a map of a key value key is a point an object of x and y points val is a creature from this reason is equals to 'test'. What I need to change in my code to get this test value from this key object ?

class Board {
    constructor() {
        this.map = new Map();
    }
    add(point, creature) {
        this.map.set(point, creature)

    }
    getVal(aX, aY) {
        console.log(this.map) // Map { Point { x: 0, y: 0 } => Creature {} }
        console.log(new Point(aX, aY)) //output: {x:0,y:0}
        console.log(this.map.get(new Point(aX, aY))) //output: undefined
        return this.map.get(new Point(aX, aY))
    }
}

class Point {
    constructor(aX, aY) {
        this.x = aX;
        this.y = aY;
    }
}

function test() {
    let board = new Board();
    board.add(new Point(0, 0), 'test');

    return cretureFromBoard = board.getVal(0, 0);
}
console.log('test()', test())

Answer 1

It needs to be an object whose equality is true when compared to the key, not just any object that happens to have the same structure and values.

For example:

a = {x:0,y:0};
b = {x:0,y:0};
console.log(a == b); // false

So you would need to keep your key object somewhere and use that:

const map1 = new Map();
var key = {x:0,y:0};
map1.set(key, 'val');

console.log(map1.get(key)); // "val"

Or use something else, with more convenient equality semantics, for the key.