why the result of this function not assigning value of 1

Question

why the result of this function is not 1?

   
function call(t) {
    t = 1;
};

var b = 0;

call(b);

console.log(b)

What do you mean by "result of this function"? That function does not return anything — Nico Haase, Sep 23 '20 at 13:39

score 2 · Answer 1 · answered Sep 23 '20 at 13:39

2

Parameters are passed by value, not by reference. From MDN:

Primitive parameters (such as a number) are passed to functions by value; the value is passed to the function, but if the function changes the value of the parameter, this change is not reflected globally or in the calling function.

answered Sep 23 '20 at 13:39

Klaycon

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1

Its always pass-by-value. In case of objects, value is the reference to an object. – Yousaf Sep 23 '20 at 13:44

score 1 · Answer 2 · answered Sep 23 '20 at 13:39

Because b is not directly accessed by the function when calling it. b is used as a parameter for the function, but it doesn't change the original varible.

The function is just changing the value, which is passed to the function inside the function. If you would like to change the variable b, you would need something like this:

var b = 0;

function call() {
    b = 1;
}

call();

console.log(b);

In this case b is 1 after execution of the function (because it referenced the variable b directly).

why the result of this function not assigning value of 1

2 Answers2