How to change a Key in Object if Key value is number?

Question

I'm new to javascript and have a question : i want to change keys if their value is number for example. What's wrong with my code?

const order = {
    wine : 100,
    vodka : 200,
    beer : 300,
    whisky : "not in stock"
};

function change(obj) {
    for (var prop in obj) {
        if (typeof obj[prop] === "number") {
            prop = "is number";
        }
    }
}

change(order);
console.log(order);

i want output to be

    is number : 100,
    is number : 200,
    is number: 300,
    whisky : "not in stock"

You aren't changing the object itself you're just creating a new local isntance in the function — , Oct 29 '20 at 07:39
@expressjs123 how can i edit it ? can you explain me please? — Max M, Oct 29 '20 at 07:40
You can't have the same key multiple times in an object. They will just overwrite eachother — Reyno, Oct 29 '20 at 07:43
Object keys should be unique. So you cannot have an object with multiple `is number` keys, you can change the values though, but thats not what you are looking right? — kiranvj, Oct 29 '20 at 07:44
@kiranvj i just want to understand how to edit keys if their value is typeof something. trying to understand it and made this example to practice — Max M, Oct 29 '20 at 07:47
@SajeebAhamed i just want to understand how to change keys if i want it . no need to give them all same names, but want to understand how it works. how to call the key, if its value is typeof something — Max M, Oct 29 '20 at 07:50
@MaxM we dont (cannot) edit keys, we add a new one and delete the old one . — kiranvj, Oct 29 '20 at 08:22

score 0 · Answer 1 · answered Oct 29 '20 at 07:42

0

When you do this

prop = "is number";

It is assigning "is number" to a variable called "prop". If you want to change the key, delete the existing key and create a new one.

Also, the keys are unique in an object. you cannot have multiple keys with same name.

function change(obj) {
    for (var prop in obj) {
        if (typeof obj[prop] === "number") {
            obj["is number"] = obj[prop];
            delete obj[prop];
        }
    }
}

answered Oct 29 '20 at 07:42

krish

40
2

The same key cannot exist in one object. – Sajeeb Ahamed Oct 29 '20 at 07:45
yes.. as the keys are unique, it will have only 1 "is number" key. And if he runs this in a loop, the "is number" will have 400 "is number"'s value will get overridden every time there is a number value. – krish Oct 29 '20 at 07:46
Yes and OP doesn't want this. He is asking something invalid. – Sajeeb Ahamed Oct 29 '20 at 07:47

score 0 · Accepted Answer · edited Oct 29 '20 at 14:44

To change a key if it's value is a number, you need to clone the key and value first. And then you need to delete the key in the object and once it's deleted it should be injected into the object again.

`function change(obj) {
    for (var prop in obj) {
        if (typeof obj[prop] === "number") {
            obj['is_number_' + obj[prop]] = obj[prop]
            delete obj[prop]
        }
    }
}`

The result should be like this : is_number_100 : 100, is_number_200 : 200, is_number_300 : 300, whisky : "not in stock"

How to change a Key in Object if Key value is number?

2 Answers2