Executing a function assigned to a variable in JS

Question

Hello.
If I create a function called Multiply, that multiplies "a" by "b" :
function Multiply(a, b) {return a * b; }
And then I assign this function to the variable "x" and I input the values 5 and 6 for "a" and "b" :
var x = Multiply(5, 6);
And then I use document.write to display the value of "x":
document.write(x);
The result will be 30. Pretty simple, right?

Well, my question is, when exactly is "return a*b" executed?
Is it when I assign this function to "x"?
Or is it calculated when I use document.write(x)?

Answer 1

After you called the function Multiply(5,6); that will be calclated🙃

Answer 2

"When exactly is 'retun a*b' executed"
~OP

As retun a*b; is a statement within function `Multiply` it'll be executed when function is called.

You need to put parantheses () after function name in order to call it. If it accepts any arguments they will go within ().

let x = function multiply(a,b){
return a*bm
}

document.write( x(2,5) );

When you print `x` it'll not execute function. Its default toString method will be invoked.

document.write(x)
output: function multiply(a,b){ return a*b }

Answer 3

You are not assigning the function itself, but the result of a function call.

So first the function is executed, then the return value 30 is stored in x.