知识 点是 Math.ceil() 和模版字符串 

 <body>
    	<ul id="ul">
            
        </ul>
        <script type="text/javascript">
            const _createPage = (allItem, pageItem) => {
                // 补全代码 queryS
                // document.querySelector
                let ul = document.querySelector('#ul')
                const length = Math.ceil(allItem/pageItem)
                let str = ''
                for (let index = 1; index <= length; index++) {
                     
                    str +=`<li>${index}</li>`
                    
                }
                ul.innerHTML = str
                
            }
         
        </script>
    </body>