Help The for loop (JS)

Question

Here is the quizz I don't understand :

Fill in the blanks to print even values from 0 to 20 using a for loop:

var x = 0;
for (; x<= ??? ; x+= ???) {
document.write(x);
}

The ??? are the two answers I need to find but I don't understand the third statement (x+=). I know x+=y means x=x+y but in this exercice it confused me.
Thanks

Answer 1

Hello there!
The 3rd statement is executed each time the loops is executed.
For example, if it's x++, every time x will increase his value of 1.
In this case, you need to find even values (2, 4, 6,....), so a hint: make a loop that will print all even numbers, by 'skipping' by 2 numbers every time. :)

For more:
https://www.sololearn.com/learn/JavaScript/1140/?ref=app

Answer 2

Thanks both of you guys, your explanations are clear and help me a lot. Now I get it but I was so frustrated that I was stuck in...a bad loop ;)
Thanks again! :)

Answer 3

Philippe Graas

You have to get even numbers till 20 so there should be x <= 20 and even numbers are those numbers which are multiple of 2 so just do x += 2

finally

for(; x <= 20; x += 2)

x += 2 means x = x + 2

so every time 2 will be increment in previous x value