How to read the values logged from built in iterables in JavaScript?

user_3555262 0
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I'm digging into Iterables and Iterators in JavaScript and wanted to understand how to read the value returned from Symbol.iterator for the built in iterables

const str = new String()
const arr = new Array()
const map = new Map()
const set = new Set()

console.log(str[Symbol.iterator]()) Returns Object [String Iterator] {}
console.log(arr[Symbol.iterator]()) Returns Object [Array Iterator] {}
console.log(map[Symbol.iterator]()) Returns [Map Entries] {  }
console.log(set[Symbol.iterator]()) Returns [Set Iterator] {  }

Would someone be able to translate the return value in each of the above cases to simple english readable format please? Thanks in advance

javascript
1 Answers

The answer is the same for each: you're getting an iterator back, which you can then use to step through the values contained in the string/object.

let str = 'Foobar'; //no need for a "constructed" string - a literal is fine
let it = str[Symbol.iterator]();
it.next().value; //"F"
it.next().value; //"o", etc

Or for the array:

let arr = [5, 7, 9];
let it = arr[Symbol.iterator]();
it.next().value; //5

---- EDIT ----

In answer to your comment, it is an iterator object. There is no explicit difference between an iterator object belonging to a string versus one belonging to a map - there are just iterables (to which all four of your examples belong) and iterators.

user_13522880
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