CODEWITHSUNDEEP
javascript
user3247345
user3247345

Reputation: 29

Array length if statement?

I made a simple Image slider in JS for practice, but for some reason the variable Amount is equal to 3, which it should be, I tested by printing 3, but for my if statements I have to divide by 2 for the first (which makes it work ((function next() )), but for the second it does not work if I divide by 2 or do Amount alone (the back() function)

I do not know why it is doing this, please can someone explain? Thanks!

var Images = ["http://www.industus.com/test/wat1.png", "http://www.industus.com/test/wat2.png", "http://www.industus.com/test/wat3.png"];
var CurrentImage = -1;
var Amount = Images.length;
function next() {
  if (CurrentImage <= Amount /2) {
    CurrentImage = CurrentImage + 1;
    document.getElementById("Picture").src = Images[CurrentImage];
  }
}
function back() {
  if (CurrentImage >= Amount /2) {
    CurrentImage = CurrentImage - 1;
    document.getElementById("Picture").src = Images[CurrentImage];
  }
}

Upvotes: 0

Views: 171

Answers (1)

Felix Kling
Felix Kling

Reputation: 817228

For going forward, you want to test whether the index is smaller than the largest valid index, with is Amount - 1

CurrentImage < (Amount-1)

For going backwards, you want to test whether the index is larger that the smallest valid index, which is 0:

 CurrentImage > 0

Upvotes: 1

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