var leftBtn=document.getElementsByClassName('btnleft')[0];
var rightBtn=document.getElementsByClassName('btnright')[0];
//获得盒子属性
var slipRight=document.getElementsByClassName('slip-right');
//单击左按钮
var count=0;
leftBtn.onclick=function(){
count>=3?count=0:count++;
for(var j=0;j<slipRight.length;j++){
slipRight[j].style.display="none";
slipRight[count].style.display="block";
}
}
//单击右按钮
rightBtn.onclick=function(){
count<=0?count=2:count--;
for(var j=0;j<slipRight.length;j++){
slipRight[j].style.display="none";
slipRight[count].style.display="block";
}
}
点击完左边按钮一直count一直等于1，点击完右侧按钮一直等于2
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<button id="butleft">左边按钮</button>
<button id="butright">右边按钮</button>
<body>
</body>
<script>
var left=document.getElementById("butleft");
var right=document.getElementById("butright");
var count=0;
left.onclick=function(){
count>=3?count=0:count++;
console.log(count);
}
right.onclick=function(){
count<=0?count=2:count--;
console.log(count);
}
</script>
</html>
无法重现你的问题，我这个demo左边0123，右边210