A simple tab development
The following methods are used
changeTabHandle function used in method 1-3

//Index of the current click button
function changeTabHandle(n) {
    for(var i=0; i<tabList.length; i++){
        tabList[i].className = '';
        divList[i].className = '';
    }
    tabList[n].className = 'active';
    divList[n].className = 'active'; 
}

1. Custom Property Name

   // Method 1: Customize attribute method
   console.log(tabList);
   for (var i = 0;i < tabList.length; i++){

      tabList[i]._f_index = i;
      tabList[i].onclick = function () {
          console.dir(this);
          changeTabHandle(this._f_index);
      }  

   }

2. es6 let

   // Method 2: var - > let
   for(let i=0; i<tabList.length; i++){

      tabList[i].onclick = function() {
          changeTabHandle(i);
      }

   }

3. closure

Method 1:

for(var i=0; i<tabList.length; i++){
     ~function (i) {
         tabList[i].onclick = function () {
             changeTabHandle(i);
         }
     }(i)
 }

Method two:

 for(var i=0; i<tabList.length; i++){
     tabList[i].onclick = function (i) {
         return function() {
             changeTabHandle(i);
         }
     }(i)
 }

1. Memory was last selected instead of emptying all + custom attributes

   beforeIndex = 0;
   for(var i=0; i<tabList.length; i++){

   tabList[i]._f_index = i;
   tabList[i].onclick = function() {
       
       tabList[beforeIndex].className = '';
       divList[beforeIndex].className = '';
       tabList[this._f_index].className = 'active';
       divList[this._f_index].className = 'active';
       beforeIndex = this._f_index;
   }

   }

5. Memory last time was the selected one, not all empty + let

for(let i=0; i<tabList.length; i++){
    tabList[i].onclick = function (params) {
        tabList[beforeIndex].className = '';
        divList[beforeIndex].className = '';
        tabList[i].className = 'active';
        divList[i].className = 'active';
        beforeIndex = i;
    }
}

github instance code https://github.com/fung-yu/js... tab in China