Why doesn't my function change value of variable?

Question

I have a problem when I try to change value of my variable.

var id = null;
async function getUser() {
    let user = document.getElementById('user').value;
    let passs = document.getElementById('pass').value;

    let res = await eel.login(user, passs)();

    let text = res[0];

    let id_res = res[1];

    if (text == 'Вы успешно авторизовались!') {
        window.location.href = 'index.html';
    } else if (text == 'Неправильное имя пользователя или пароль') {
        alert(text);
    }

    var copy = $.extend( {}, id );
    copy = id_res; // that's my problematic part

    alert(id); // allerting updated variable
}

Then, when I try to use "id" variable, it still returns "null".

async function createTask() {
    let task = document.getElementById('need_task').value;

    let result = await eel.create_task(copy, task);
    alert(copy); // got error, that copy is undefined
}

In addition, in my html, I added document.getElementById('btn').addEventListener('click', getUser); and "document.getElementById('but').addEventListener('click', createTask);" to activate my functions.

As you can see, I use python eel library. So I guess, that my mistake is with that eel. I will appreciate any of your hepl!

`var id` declares a *new* variable called `id` which shadows the declaration `var id` from outside. — VLAZ, Aug 20 '21 at 13:26
But when I run "alert(id)" in my first function, value has changed — Нурмухамед Бименов, Aug 20 '21 at 13:29
Moaud louhichi, yes, when I do consol.log(res[1]), I get right value. — Нурмухамед Бименов, Aug 20 '21 at 13:33
try removing keyword 'var' from this line 'var id = id_res;' — Muhammad Ehtesham Anwar, Aug 20 '21 at 13:33
put `id = id_res` instead of `var id = id_res;` in `getUser()` because `var id` will create new variable in memory so, `id` in `getUser()` global `id`are different that's why it's remains `null` in the `createTask()`. — Mahesh, Aug 20 '21 at 13:35
equals operator `=` creates a reference to res[1] but after `getUser()` is done `res` is destroyed. read this https://stackoverflow.com/questions/18829099/copy-a-variables-value-into-another — Muhammad Ehtesham Anwar, Aug 20 '21 at 13:39

score 1 · Answer 1 · answered Aug 20 '21 at 13:44

You should read this to understand copy in javascript: Copy a variable's value into another

var id = null;
async function getUser() {
    let user = document.getElementById('user').value;
    let passs = document.getElementById('pass').value;

    let res = await eel.login(user, passs)();

    let text = res[0];

    let id_res = res[1];

    if (text == 'Вы успешно авторизовались!') {
        window.location.href = 'index.html';
    } else if (text == 'Неправильное имя пользователя или пароль') {
        alert(text);
    }

    id = id_res; // remove var

    alert(id); // will alert updated value.
}

no need to change 2nd function now

I had read thisinformation, but I guess that didn't get it. I edited my code after reading, please look at it. — Нурмухамед Бименов, Aug 20 '21 at 14:06

Why doesn't my function change value of variable?

1 Answers1