Iterating with for... in loop in JavaScript

Question

I have an empty array called objToArray. I'm trying to use a for-in-loop to fill the array with all of the numbers from a hash checkObj object, if the keys have a value greater than or equal to 2.

const checkObj = {
 oddNum: 1,
 evenNum: 2,
 foundNum: 5,
 randomNum: 18
};
const objToArray = [];
for (let values in checkObj) {
 if (Object.values(checkObj) >=2 ) {
 objToArray.push(checkObj.values())
 }
}
console.log(objToArray);

So far, I get objToArray as an empty array even though it should contain three elements and should equal [2, 5, 18].

• Karan: Replace Object.values(checkObj) >=2 with checkObj[values] >= 2 and objToArray.push(checkObj.values()) with objToArray.push(checkObj[values]).
• Codestudio: This works great. So basically, checkObj[values] is equivalent to the value in the hash object?
• Karan: Yes, in your checkObj you can access oddNum property value with checkObj.oddNum or checkObj["oddNum"] or for let key = "oddNum"; checkObj[key] will return same value.

Answer 1

Try with Object.values(checkObj).filter(x => x >= 2);.

1. Get array of all values with Object.values(checkObj).
2. Filter array and get value >= 2 with .filter(x => x >= 2).

If you want to use for ... in loop then it iterates over key so you can get value with obj[key]. As you have declared for (let values in checkObj) values object will hold key of checkObj. So you can access value with checkObj[values].

Check output below.

const checkObj = {
 oddNum: 1,
 evenNum: 2,
 foundNum: 5,
 randomNum: 18
};
// Approach 1
let result = Object.values(checkObj).filter(x => x >= 2);
console.log(result);
// Approach 2
const objToArray = [];
for (let values in checkObj) {
 if (checkObj[values] >= 2) {
 objToArray.push(checkObj[values]);
 }
}
console.log(objToArray);

Answer 2

Is this you wanted?

The for...in statement iterates over all enumerable properties of an object that are keyed, it should be key rather than values.

const checkObj = {
 oddNum: 1,
 evenNum: 2,
 foundNum: 5,
 randomNum: 18
};
const objToArray = [];
for (let key in checkObj) {
 if (checkObj[key] >= 2) {
 objToArray.push(checkObj[key])
 }
}
console.log(objToArray)

Answer 3

Try this:

const checkObj = {
 oddNum: 1,
 evenNum: 2,
 foundNum: 5,
 randomNum: 18
};
 
const objToArray = [];
for (let [key, value] of Object.entries(checkObj)) {
 // console.log(`${key}: ${value}`);
 if(value>=2){
 objToArray.push(value);
 }
}
console.log(objToArray);

• Karan: As you are already iterating over key of checkObj you don't need to check if (checkObj.hasOwnProperty(property)) {, it will always true.

Answer 4

Try this

const checkObj = {
 oddNum: 1,
 evenNum: 2,
 foundNum: 5,
 randomNum: 18
};
let objToArray = [];
objToArray = Object.values(checkObj).filter(elem => elem >= 2);
console.log(objToArray);

• viam0Zah: Besides showing a working solution to the problem, it's worth explaining what was incorrect in the OP's proposal so that they can learn from it.
• Bhuwan Pandey: @viam0Zah Thank You, surely I'll keep that practice in future

Answer 5

try this: I hope you got it ..

let checkObj = {
 oddNum: 1,
 evenNum: 2,
 foundNum: 5,
 randomNum: 18
};
let objToArray = [];
for (let values of Object.values(checkObj)) {
 console.log(values);
 if (values >=2 ) {
 objToArray.push(values)
 }
}

Answer 6

const checkObj = {
 oddNum: 1,
 evenNum: 2,
 foundNum: 5,
 randomNum: 18
};
const objToArray = []; 
//changing the loop into a foreach loop that iterates over the keys
Object.keys(checkObj).forEach((key => {
 if (checkObj[key]) {
 objToArray.push(checkObj[key])
 }
}))

• Cedervall: ah right, that's correct, didn't think it through. Editing.