Global variable being modified inside function

Asked May 19 '17 at 12:43

Active May 19 '17 at 12:43

Viewed 36 times

I might be getting things wrong, but I know at least that I don't want this behaviour.

I have a while loop in JS, inside a function. Global vars are passed into the function.

Yet when the loop runs, the global variables are changed, alongside the ones inside the function.

Example

var arr = [0, 1, 2, 3, 4, 5];
var i = 0;

function test(myArr)
{
    while(i < 2)
    {
        myArr.pop();
        i++
    }

    console.log(arr);
    console.log(myArr);
}

test(arr);

The console spits out

[ 0, 1, 2, 3 ]
[ 0, 1, 2, 3 ]

Why is the global being affected?

asked May 19 '17 at 12:43

Mr Pablo

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You're passing a reference to the object. `myArr === arr` – George May 19 '17 at 12:44
Because you *pop*'ed two of its members. – RobG May 19 '17 at 12:45
[This answer](//stackoverflow.com/a/3638034/962603) I think answers your question. – Just a student May 19 '17 at 12:46
@George what do you mean? Where should I put myArr === arr? – Mr Pablo May 19 '17 at 12:55
@RobG I pop'd myArr, not arr..... – Mr Pablo May 19 '17 at 12:55
The value of *arr* is a reference to the array. You pass that value to *myArr* so they both reference the same array, hence `arr === myArr`. ;-) – RobG May 19 '17 at 14:34

Global variable being modified inside function

0 Answers0