looping an array within an array

Question

I'm trying to make a loop where one value goes up while the second goes down.. I cant figure it out. As far as I can see checkNumber counts down correctly, and x and i are incorrect

I know i'm making a silly mistake somewhere but I'm brand new to coding

var checkNumber = 5;
for (var x = 0; x < 5; x++) {
 for (var i = 0; i < checkNumber; i++) {
 console.log(checkNumber);
 checkNumber = checkNumber - 1;
 console.log("x",x,"i",i);
 }
}

• Sudheesh Singanamalla: What do you mean by incorrect? What is the output you're expecting?
• Andreas: Which language is it? Why have you tagged two languages?

Answer 1

Just use a single loop and take the difference of the max value and the actual value (minus one, because of the zero based nature) for the second value.

var value = 5,
 i;
for (i = 0; i < value; i++) {
 console.log(i, value - i - 1);
}

• thx4help: this makes sense, i was probably trying to over complicate it. thanks.

Answer 2

I'm assuming you're trying to do this:

var checkNumber = 5;
for (var x = 0; x < checkNumber; x++) {
 for (var i = checkNumber - 1; i >= 0; i--) {
 console.log(checkNumber);
 console.log("x", x, "i", i);
 }
}

This will start i at 4 (minus one to avoid index issues if that's what you're looking for, otherwise remove the -1) and go down to 0.

The first loop will count up until 4.

The trick is to use i-- and set i to something higher, then stop the loop with the second condition in the for.

Does that make sense?

• thx4help: thanks for explaining a bit more. i've found this website to not be very easy on beginners and so it's nice to have people like yourself who take the time to help :)

Answer 3

This will make i start at 0 and j start at 4. While i goes up to 4, j will go down to 0.

var checkNumber = 5;
for(var i = 0, j = checkNumber - 1; i < checkNumber; i++, j--){
	console.log(i + " " + j);
}