老師我在 item.addEventListener中的 li.children[1].classList.remove("active");一直報(bào)錯(cuò)說 Cannot read property 'classList' of undefined
class?Menu?{
??constructor(id)?{
????this.box?=?document.querySelector(id)
????this.ul?=?this.box.querySelector("ul");
????this.lis?=?this.box.querySelectorAll("li");//因?yàn)橛卸鄠€(gè)li結(jié)點(diǎn),所以加All
????this.subMenu?=?this.box.querySelectorAll(".sub-menu");
????this.time1?=?null;
????this.time2?=?null;
????this.init();//調(diào)用init
??}
??init()?{
????console.log("menu");
???
????this.lis.forEach((item)?=>?{
??????
??????item.addEventListener("mouse",?(e)?=>?{
????????let?li?=?e.target;
????????console.log("mouse");
??????????this.time1=setTimeout(()=>
??????????{
????????????this.subMenu.forEach((item)=>
????????????{
??????????????item.classList.remove("active");
????????????})//在這里用循環(huán)
?????????????if(this.time1?!=null)
?????????????{
???????????????clearInterval(this.time1);
?????????????}
????????????li.children[1].classList.add("active");//children[1]就是li下的第二個(gè)子類
??????????},200)
??????})
????});
????//item.addEventListenneer代表鼠標(biāo)觸發(fā)事件，e有點(diǎn)像函數(shù)一樣包含其中的事件
????this.lis.forEach((item)?=>?{
??????item.addEventListener("mouseleave",?(e)?=>?{
????????let?li?=?e.target;
????????console.log("mouseleave");
????????this.time2=setTimeout(()?=>?{
??????????this.subMenu.forEach((item)=>
????????????{
??????????????item.classList.remove("active");
????????????})//在這里用循環(huán)
??????????li.children[1].classList.remove("active");
????????},200)
??????})
????});
??}
}
2021-02-14
你發(fā)的代碼錯(cuò)誤百出，核對一下代碼吧。
報(bào)錯(cuò)是發(fā)生在倒數(shù)第二個(gè)remove那里的，第一個(gè)循環(huán)的事件是mouseenter不是mouse，而且你第二個(gè)循環(huán)那里怎么有兩個(gè)循環(huán)？而且怎么是item.classList?