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JavaScript

Posted by Gabriel D. Celery
Gabriel D. Celery
13,810 Points

Function argument-output issue

Okay so I was experimenting with function arguments and I ran into an issue. Wanted to write a function that simply takes a boolean as an argument then switches it true to false or false to true.

Except after calling the function it doesn't work as intended. So how shall I modify the code below to make it work?

var boolean = true;

var changeBoolVal = function(param){
    param = !param;
    console.log(param); /*this returns false as intended*/
}

changeBoolVal(boolean);

console.log(boolean); /*this still returns true*/

1 Answer

tootiemcflow
tootiemcflow
5,601 Points
tootiemcflow
tootiemcflow
5,601 Points

Your function works fine! The problem is you're simply logging/printing the value of the boolean variable on line 1. you can see what I mean by removing the code in-between. 

var boolean = true;

console.log(boolean);
// => ture

To fix this, redefine your boolean variable by storing the function call to it. 

var boolean = true;

var changeBoolVal = function(param){
    param = !param;
    console.log(param);
}

boolean = changeBoolVal(boolean);

console.log(boolean);
// => false

Alternatively, you could just throw the function call inside the console.log function.

console.log(changeBoolVal(boolean);
// => false
Gabriel D. Celery
Gabriel D. Celery
13,810 Points

I see. But the point would have been to write a function that takes any boolean variable as an argument and changes the value of that variable. (Sorry if the original question wasn't clear)

With this method I am still stuck at writing an extra line outside the function where I assign the output of the function to the variable. So if I have one hundred variables I have to write one hundred extra piece of line.