一.知识点回顾
①事件委托

父元素.onclick = function（e）{
e = window.event || e.event; //浏览器兼容性
    console(e.target) 
}

②字符串方法
trim() //删除前置以及后缀的所有空格，然后返回结果;
有兴趣的话前面文章有封装方法可参考

    var str = "  hello world   ";
    var newStr = str.trim();
    console.log(newStr);  //"hello world"

二.代码详情

1. html详情

 <div>
        <ul id="content"></ul>
        <textarea name="" id="text" cols="30" rows="10"></textarea>
        <button id="go">发表</button>
 </div>

2.css简写

    * {
        list-style: none;
    }

    .active {
        display: none;
    }

3.js代码详情

        var ul = document.getElementById('content')
        var text = document.getElementById('text')
        var go = document.getElementById('go')
        var content = document.getElementById('content')

        function getHtml() {

            var time = new Date();
            var timer = `${time.getFullYear()}-${time.getMonth() +1}-${time.getDate()} 
            ${time.getHours()}:${time.getMinutes()}:${time.getSeconds()}`
            var text_val = text.value.trim();
            if (text_val == '' && text_val.length == 0) {
                return;
            }
            console.log(text_val, text_val.length)
            ul.innerHTML += `<li><span>${timer}</span>${text_val}<button>删除</button></li>`;
            text.value = '';
        }
        go.addEventListener('click', function () {
            getHtml()
        })
        content.onclick = function (e) {
            e = window.event || e.event;
            console.log(e.target)
            if (e.target.nodeName == 'BUTTON') {
                e.target.parentNode.classList.add('active')
            }
        }
        window.onkeydown = function (e) {
            e = window.event || e.event;

            if (e.keyCode == 13) {
                getHtml()
            }
        }

如有错误请指正，抱拳了老铁！！！