Unable to delete map entries using map.delete() function-CodePudding

I'm trying to delete the entry with key '1' in the map. Can anyone tell me why is map.delete(1) returning false and the entry is not being deleted.

let nums = [1,1,1,2,2,3]
let map = new Map();
    for (let num of nums) {
        if (num in map) {
            map[num]  ;
        } else {
            map[num] = 1;
        }
    }
    console.log(map) // Map(0) { '1': 3, '2': 2, '3': 1, '4': 3 }
    console.log(map.delete(1)); // false
    console.log(map) // Map(0) { '1': 3, '2': 2, '3': 1, '4': 3 }

CodePudding user response：

let nums = [1,1,1,2,2,3, 4]
let map = new Map();
for (let num of nums) {
    if (num in map) {
        map.set(num, map.get(num)  );
    } else {
        map.set(num, 1)
    }
}
console.log(map)
console.log(map.delete(1))
console.log(map)

CodePudding user response：

You need to use map.get() and map.set() instead of bracket syntax. Assigning properties to a map object doesn't actually use the Map, and is why map.delete() does nothing.

Either use a Map:

const map = new Map();
for (let num of nums) {
    if (map.has(num)) {
        map.set(num, map.get(num) 1);
    } else {
        map.set(num, 1);
    }
}
map.delete(1);

Or (ab)use an object as a collection:

const map = Object.create(null);
for (let num of nums) {
    if (num in map) {
        map[num]  ;
    } else {
        map[num] = 1;
    }
}
delete map[1];