javascript - Is it possible to change the value of the function parameter?

Question

I have one function with two parameters, for example function (a,b). I want to within the function, take the value of b, and replace that with c. I was thinking of something like $(b).replaceWith(c), but it didn't work out. I know I can create a new variable within the function with the new value, but is it possible to change the value of b itself? Is something like this possible. Or are the parameters set in stone?

Let me try to explain what I am trying to do. There are three functions, one overarching function and then two functions within it which are triggered by toggle event. And I want the second function to do something to get a value and pass it on to the third function. So here would be the code

function(a,b){

    $('selector').toggle(

        //I want this to gather a value and store it in a variable
        function(){},

        //and I want this to accept the variable and value from the previous function
        function(){}
    )}

The only way I can think of doing this is to add a parameter c for the overarching function and then modify it with the first function and have the new value pass on to the second function.

Answer 1

You cannot pass explicitly by reference in JavaScript; however if b were an object, and in your function you modified b's property, the change will be reflected in the calling scope.

If you need to do this with primitives you need to return the new value:

function increaseB(b) {
  // Or in one line, return b + 1;
  var c = b + 1;
  return c;
}

var b = 3;
console.log('Original:', b);
b = increaseB(b); // 4
console.log('Modified:', b);