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JavaScript

William Hurst
William Hurst
25,074 Points
Posted by William Hurst
William Hurst
25,074 Points

stevenS = stevenJ; set size

The Set 

let classroom = new Set();

let stevenJ = { name: 'Steven', age: 22 },
    sarah = { name: 'Sarah', age: 23 },
    stevenS = stevenJ;

classroom.add(stevenJ);
classroom.add(sarah);
classroom.add(stevenS);

console.log('classroom size:', classroom.size);

console.log('classroom size:', classroom.size); outputs: 

classroom size: 2

Check if a value exists using has:

if (classroom.has(stevenJ)) console.log('stevenJ is in the classroom');
if (classroom.has(sarah)) console.log('sarah is in the classroom');
if (classroom.has(stevenS)) console.log('stevenS is in the classroom');

Outputs: 

stevenJ is in the classroom
sarah is in the classroom
stevenS is in the classroom

Why do 3 values exist with has, but using size shows 2 values?

1 Answer

Sean T. Unwin
Sean T. Unwin
28,690 Points
Sean T. Unwin
Sean T. Unwin
28,690 Points

Why do 3 values exist with has, but using size shows 2 values?

Because stevenS = stevenJ and Set.prototype.size returns unique elements in the Set.

Reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set/size