如何反转 javascript 图片轮播的方向？

Question

I have an image carousel that by default rotates to the right. using setInterval() and changing the image every few seconds. I created two setInterval functions, one to rotate to the right and one to rotate to the left.

I then created an html arrow and added an onclick call to it to call the specific setInterval I wanted. The problem is the previous setIntervals dont turn off when new ones are called. I tried to use clearInterval but it wasnt working.

My code looks like:

const left_arrow = document.querySelector("#arrow");

  var rotateRight = setInterval(()=>{
   // do stuff
}, 3000)
 var rotateLeft = setInterval(()=>{
   // do stuff
}, 3000)

left_arrow.onclick = rotateLeft();
right_arrow.onclick = rotateRight();

I basically want to have the ability to click an arrow and have it rotate the flow of my images by calling different setInterval functions. I cant use any frameworks. Thank you.

Answer 1

SetInterval only executes an action every x milliseconds , so with your code you are going left and then right every three seconds. Here is my code that I think would work

direction = "right"

setInterval(()=>{
   if(direction === "right") {
      //do stuff to rotate right
   } else {
      //do stuff to rotate left
   }
}, 3000)

left_arrow.onclick = () => {
   direction = "left";
};
right_arrow.onclick = () => {
   direction = "right";
};

So explaining what the code is doing the variable direction stores which direction the carousel should move, the code inside setInterval runs every 3 seconds, if the direction is right you run some code, otherwise you run other code. When you click the buttons it just sets the directions.

Answer 2

I think clearInterval will work on your scenary, may be you clearInterval on wrong time. if you're not sure,please paste more code.

secondly, const left_arrow = document.querySelector("#arrow"); #arrow element are named left_arrow, i don't know what is your element id for right_arrow, may be that's also a problem.

Answer 3

As @Dominik comments, the solution to stop the original interval is to use clearInterval

when you call setInterval it

const left_arrow = document.querySelector("#arrow");

let currentInterval = null;

function rotateRight(){
    return setInterval(()=>{ 
       clearInterval(currentInterval)
       // do stuff
    }, 3000)
}

function rotateLeft(){
    return setInterval(()=>{ 
       clearInterval(currentInterval)
       // do stuff
    }, 3000)
}

left_arrow.onclick = ()=> {currentInterval = rotateLeft();}
right_arrow.onclick = ()=> {currentInterval = rotateRight();}