In javascript, ++i does what? See example

Question

function sum(i) { return ++i; }

Answer 1

// Increment operators
x = 1;
y = ++x; // x is now 2, y is also 2
y = x++; // x is now 3, y is 2

// Decrement operators
x = 3;
y = x--; // x is now 2, y is 3
y = --x; // x is now 1, y is also 1

Answer 2

https://www.sololearn.com/Discuss/407846/?ref=app

Answer 3

ok, but...

function sum(i) {
return ++i;
}
for (var i = 0; i <= 1; i++) {}
document.write(sum(i));

returns 3. why? was my next question.
but i just realized:

the for loop runs twice, this sets i to 2.
then sum(i) increases it to 3.

thanks for all the answers.

Answer 4

The ++ before the i is used to increase i by one (it can be also after the i like i++)