CODEWITHSUNDEEP
javascriptiterator
Jacques de Hooge
Jacques de Hooge

Reputation: 6990

How do iterate through ALL attributes inc. e.g. [Symbol.iterator]

Following code

a = {
    b () {return 3;},
    [Symbol.iterator] () {return 4;}
};

console.log (a ['b']);
console.log (a [Symbol.iterator]);

console.log (111);
for (var attrib in a) {
    console.log (attrib);
    console.log (a [attrib]);
}
console.log (222);

prints

function b() {return 3;}
function () {return 4;}
111
b
function b() {return 3;}
222

Why is the second function, returning 4 not printed in the for loop. How can I make a for-loop where all attributes are printed, including the special ones such as [Symbol.iterator]?

N.B. The question is not how to write a correct iterator function, I know I haven't done that.

Upvotes: 1

Views: 34

Answers (1)

Azamantes
Azamantes

Reputation: 1451

Symbol.iterator is a Symbol and you cannot list them like that, you have to use Object.getOwnPropertySymbols(your_object) to list them.

For ... in ... loop lists object's properties indeed but symbols are a bit different kind of beast and they require special treatment.

Upvotes: 2

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