一、备选字符集
var str ="上海,上天,上哪里去";var reg =/上[海天]/gconsole.log(str.replace(reg,"*"));  // *,*,上哪里去var reg = /[上天哪]/gvar str = "上海,上天,上哪里"console.log(str.replace(reg,"*"));  // *海,**,**里var str = "我去,我草,你这游戏打的太牛逼了"var reg = /[去草]|牛逼/gconsole.log(str.replace(reg,"*"));  // 我*,我*,你这游戏打的太*了var res = "ajkdgkbcj128973489"var reg = /[0-9]/gconsole.log(res.replace(reg,"*"));  // ajkdgkbcj*********var str = "hello"var reg = /[el]o/gconsole.log(str.replace(reg,"*"));  // hel*
二、转义字符
var str = "https://www.baidu.com"var str2 = "http://www.baidu.com"var reg = /(http|https):\/\/[w]{3}\.baidu\.com/console.log(reg.test(str));console.log(reg.test(str2));
三、指定匹配的位置
// 电话var num = "13897932473123"var reg = /^1[3-9]\d{9}$/console.log(reg.test(num));
<input type="text" id="input"><script>  /* 去除开头结尾的空格 */  var res = []    var reg = /^\s+|\s+$/g;    var input = document.getElementById("input")    input.onkeydown = function(event){    if(event.keyCode == 13){      var str = this.value      res.push(str.replace(reg,""))      console.log(res);    }    }</script>
四、非
var str = "hello210874"var reg = /[^a-z]/gconsole.log(str.replace(reg,""));  // hellovar str = "<p>我是p标签</p>。<div>我是div</div>"var reg = /<[^<>]+>/gconsole.log(str.replace(reg,""));  // 我是p标签。我是divvar str = "https://movie.douban.com/subject/1292052/"var reg = /[^\d+]/gconsole.log(str.replace(reg,"")); // 1292052
五、邮箱验证
<input type="text" id="email" placeholder="请输入邮箱">    <script>        var e=document.getElementById("email")        e.onkeyup=function(event){            if(event.keyCode==13){                var value=this.value.trim();                var reg=/^[\w]+@[0-9a-z]+\.[a-z]+$/;                console.log(reg.test(value))            }        }    </script>
六、密码验证
<input type="password" id="email" placeholder="请输入密码">
    <script>
        var e=document.getElementById("email")
        e.onkeyup=function(event){
            if(event.keyCode==13){
                var value=this.value.trim();
              // 输入六位数密码
                var reg=/^\d{6}$/;
                console.log(reg.test(value))
            }
        }
    </script>
七、账户密码
<input type="password" id="email" placeholder="请输入密码">
    <script>
        var e=document.getElementById("email")
        e.onkeyup=function(event){
            if(event.keyCode==13){
                var value=this.value.trim();
              // 以字母开头,后面是数字,数字至少包含5位
                var reg=/^[a-zA-Z]+\d{5,}$/;
                console.log(reg.test(value))
            }
        }
    </script>
八、用户名验证
<input type="text" id="email" placeholder="请输入用户名">
    <script>
        var e=document.getElementById("email")
        e.onkeyup=function(event){
            if(event.keyCode==13){
                var value=this.value.trim();
                var reg=/^[a-zA-Z]{1,8}$/;
                console.log(reg.test(value))
            }
        }