9-4 身份证规则

 <script>
        //42........x
        //42 112620001126171 x
        //42\d{15}(\d|x)
        var str = "42110619881024307x";
        var res = /^42\d{15}[\dx]$/;
        console.log(res.test(str))
    </script>

  <input type="text" placeholder="请输入密码" id="app">
    <script>
        /*
        密码
        必须包含大写小写至少6位数字且以大写字母开头
        */
        var reg = /^[A-Z]+[a-z]+\d{6,}$/
        $("#app").keyup(function(event){
           if(event.keyCode ==13){
               var value = $(this).val();
               console.log(reg.test(value))
           }
       })
    </script>

指定匹配位置

  <script>
        /*
        */
       var str = "1fiddewew"
       var reg = /^[0-9]+/
       console.log(reg.test(str))
       console.log(/\d+$/.test(str))
       var str = "        hello           ";
       var reg = /(^\s+)|(\s+$)/g
       console.log(str.trim())
       console.log()
    </script>

非

 <script>
        var str = "abc123";
        var reg = /[^abc]/g;
        console.log(str.replace(reg,"*"))
        var test = "?@hello123-";
        /*123*/
        var reg = /[^\d]/g;
        console.log(test.replace(reg,"*"))
    </script>