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天蓬老师批改状态：合格
老师批语：
<body><ul><li>item1</li><li>item2</li><li>item3</li><li>item4</li><li>item5</li></ul><script>//事件代理: 也叫"事件委托"const lis = document.querySelectorAll("li");document.querySelector("ul").addEventListener("click", ev => {//事件绑定者console.log(ev.currentTarget);//事件触发者,通常是"事件绑定者"的子元素console.log(ev.target.innerHTML);});</script></body>
<body><label>请留言: <input type="text" name="message" /></label><ol id="list"></ol><script>//获取元素const msg = document.querySelector("input");const list = document.querySelector("#list");msg.onblur = ev => {console.log(ev.currentTarget);};msg.onkeydown = ev => {// ev.key: 键盘事件中,key表示按下的键名if (ev.key === "Enter") {//非空判断if (ev.currentTarget.value.length === 0) {alert("内容不能为空");} else {//创建包括留言内容的html字符串let str = `<li>${ev.currentTarget.value}<button onclick="del(this)">删除</button></li>`;//最新留言应该始终做为第一条插入list.insertAdjacentHTML("afterbegin", str);//请空上一条留言ev.currentTarget.value = null;}}};//删除留言function del(ele) {return confirm("是否删除?") ? (ele.parentNode.outerHTML = null) : false;}</script></body>
// 1. concat()拼装let str = "html".concat(" css ", "php !", 888);console.log(str);str = "html css php !";console.log(str);// 2. slice(start, end):取子串str = "hello php.cn";let res = str.slice(0, 5);console.log(res);//默认全部拿出来res = str.slice(0);console.log(res);res = str.slice(6);console.log(res);res = str.slice(-6);console.log(res);res = str.slice(-6, 9);console.log(res);// 正方向从0开始,反方向从-1开始res = str.slice(-6, -3);console.log(res);//3. substr(start, length)res = str.substr(0, 5);console.log(res);res = str.substr(-6, 3);console.log(res);// 4. trim():删除二端空格let psw = " root888 ";console.log(psw.length);psw = " root888 ";console.log(psw.trim().length);// 5. 将字符串打成数组res = str.split("");console.log(res);// 比如说从邮箱中解析出用户和和邮箱地址res = "admin@php.cn".split("@");console.log(res[0]);console.log(res[1]);</script>
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