How to get the size of keys in map?

Question

Lets say I have this map:

var myMap = new Map();
myMap.set('0', 'foo');
myMap.set(1, 'bar');
myMap.set({}, 'baz');

var size= myMap.keys().size(); // wrong. 

console.log(size); //Looking for 3 because there are 3 keys

Is there a way? Or any alternative? Much appreciated.

Answer 1

You could read the Map#size property for the count of items.

var myMap = new Map;
myMap.set('0', 'foo');
myMap.set(1, 'bar');
myMap.set({}, 'baz');

var size = myMap.size;

console.log(size); // 3
console.log([...myMap.keys()]); // get all keys

Answer 2

keys() returns an iterator of map keys. It should be iterated first and converted to array in order for its length to be known. This is unnecessary, since keys count is equal to entries count, and the latter is already known:

[...myMap.keys()].length === myMap.size

Answer 3

You can get the size of a map by using its size property:

var size = myMap.size;

Answer 4

You can just do:

var size = myMap.size;