题解 | #分页#

function Pagination(container, total, current) {
this.total = total;
this.current = current;
this.html = html;
this.val = val;
this.el = document.createElement('ul');
this.el.className = 'pagination';//TODO: 创建分页组件根节点
if (!this.el) return;

    this.el.innerHTML = this.html();
    container.appendChild(this.el);
    if(this.total <= 1){
        this.el.className = 'hide';
    }//TODO: 判断是否需要隐藏当前元素

    function html() {
        var inHtml = '';
        if (this.total <= 1) return '';
        else if(this.total <= 5){
            for(var i = 1;i <= this.total;i++){
                if(i == this.current){
                    inHtml += `<li class = 'current'>${this.current}</li>`;
                }
                else{
                    inHtml += `<li>${i}</li>`;
                }
            }
        }
        else if(this.current <= 3){
            for(var i = 1;i <= 5;i++){
                if(i == this.current){
                    inHtml += `<li class = 'current'>${this.current}</li>`;
                }
                else{
                    inHtml += `<li>${i}</li>`;
                }
            }
            inHtml += '<li>末页</li>';
        }
        else if((this.total - this.current + 1) <= 3){
            inHtml += '<li>首页</li>';
            for(var i = (this.total - 4);i <= this.total;i++){
                if(i == this.current){
                    inHtml += `<li class = 'current'>${this.current}</li>`;
                }
                else{
                    inHtml += `<li>${i}</li>`;
                }
            }
        }
        else{
            inHtml += '<li>首页</li>';
            for(var i = (this.current - 2);i <= (this.current + 2);i++){
                if(this.current == i){
                    inHtml += `<li class = 'current'>${this.current}</li>`;
                }
                else{
                    inHtml += `<li>${i}</li>`;
                }
            }
            inHtml += '<li>末页</li>';
        }
        //TODO: 生成组件的内部html字符串
        return inHtml;
    }

    function val(current) {
        if (arguments.length === 0) return this.current;
        if (current < 1 || current > this.total || current === this.current) return;
        this.current = current;
        this.el.innerHTML = this.html();
    };
    }

对着条件写，就行了，
就是不知道那个val有什么用，望大佬讲解。