Output

Question

Plese explain me the output for the following code:

function addOne(x){
x--;
var y = x++;
var z = ++y;
return z - x;
}
addOne(5);

The output is 0.

Answer 1

For this you must learn about postfix and prefix in javascript

++i (Pre increment): It will increment the value of i even before assigning it to the variable i.

i++ (Post-increment): The operator will return the variable value first (i.e, i value) then only i value will incremented by 1.

And now apply it to your code.
Hope it will helpful for you.

Answer 2

1) addOne(5) -> x = 5

2) x-- -> x = 4

3) var y = x++ -> first y = x -> y = 5, then x++ -> x = 6

4) var z = ++y -> first ++y -> y = 6, then z = y -> z = 6

5) return z - x = 0 - the output.

Prefix:
++x do incrementing x (adding 1) before assignment or returning (++ is at first place, before x)

Postfix:
x++ do incrementing after assignment (++ is at second place, after x)

Answer 3

x = 6, y = 6, z = 6

You are getting output as z - x,
z - x = 6 - 6
= 0

Hence, you are getting answer as 0.

To know how the value of all variable came 6, see Максим Казадаев's explanation.

Answer 4

Which variable value do you need x, y or z?

Answer 5

ok ok all three

Answer 6

Thanks everyone 😊

Answer 7

Максим Казадаев one small correction......
Values of x and z are not 6..... rather it goes upto 5 after all operations.......try it by applying console.log() after each operation in your browser.......I tried it out