Hash map with linear probing

Map.js

class Map {
    constructor(loadfactor = 0.7) {
        this.size = 0;
        this.loadfactor = 0.7;
        this.entries = new Array(1);
    }

    put(key, value) {
        this.resizeIfNecessary();
        for(var i = key.hashCode();; i++) {
            const location = i % this.entries.length;
            console.log(this.entries[location]);
            if(!this.entries[location]) {
                this.entries[location] = {key: key, value: value};
                this.size++;
                break;
            } else if(this.entries[location].key === key) {
                this.entries[location].value = value;
                break;
            }
        }
    }

    get(key) {
        const hash = key.hashCode()
        for(var i = hash; i < (hash + this.entries.length); i++) {
            const location = i % this.entries.length;
            const entry = this.entries[location];
            if(!entry) return null;
            if(entry && entry.key === key) return entry.value;
        }
    }

    resizeIfNecessary() {
        if(this.entries.length * this.loadfactor > this.size) return;
        const old = this.entries;
        this.size = 0;
        this.entries = new Array(old.length * 2);
        for(var i = 0; i < old.length; i++) {
            if(old[i]) this.put(old[i].key, old[i].value);
        }
    }
}

String.prototype.hashCode = () => 42