How to increment a value in a JavaScript object?

Question

var map = {};
map[key] = value;

How can I

• assign value 1 if key does not yet exist in the object
• increment the value by 1 if it

Answer 1

function addToMap(map, key, value) {
    if (map.has(key)) {       
        map.set(key, parseInt(map.get(key), 10) + parseInt(value, 10));
    } else {
        map.set(key, parseInt(value, 10));
    }       
}