Doubt on the banner

Question

This Banner is working properly, but I just wanted to understand this account: (bannerAtual + 1) % 3 where q: 'Banneratual = 0' then, (0 + 1) = 1 % 3 = 0,3333.... someone explains to me why to change value = 1 that would be the next array?

var banners = ["imagem 1.jpg","imagem 2.jpg", "imagem 3.jpg"]
var bannerAtual = 0

function trocarBanner(){
	bannerAtual = (bannerAtual + 1) % 3
	document.querySelector('.destaque_img').src = banners[bannerAtual]
}

setInterval(trocarBanner, 2000)

<img class="destaque_img" />

Answer 1

The operator % is not division. It returns the "rest" of the division of the first number by the second, when the first is equal to or greater than the second. If the first is smaller, it returns the first:

1%3 = 1 // 1 (primeiro número, à esquerda de %) é menor que 3

3%3 = 0 // resto 0 (3 dividido por 3 = 1, resta 0)

5%2 = 1 // resto 1 (5 dividido por 2 = 2, resta 1)

References at this link.