Why is it showing "undefined"???

Question

let obj = {a: 1, b: 2, c: 3};

for( let key in obj ){
console.log(obj.key);
}

Why , undefined?

Answer 1

With (for/in) loops you need to us the bracket notation to retrieve the value from the object.

https://code.sololearn.com/WKtS9CO2tvXf/?ref=app

Answer 2

let obj = {a: 1, b: 2, c: 3};
for(let val of Object.values(obj)){
console.log(val);
}

(You can do the same with keys.)