// 字面量的方式   var patt = /匹配规则/修饰符;     / --> 边界的意思

  //创建一个正则表达式，可以用来查看指定字符串中是否含有数字

  var patt = /[0-9]/;

  var str = "hello1234";

  var str2 = "hello";

  //test()  检测指定字符串中是否含有某种匹配规则  返回一个布尔值

 var flag = patt.test(str);

 console.log("flag:",flag);//flag: true

  flag = patt.test(str2);

  console.log("flag:",flag);//flag: false

  // new关键字     var patt = new RegExp(/匹配规则/,修饰符);

  var reg = new RegExp(/\d/);

  console.log(reg.test(str));//true

  console.log(reg.test(str2));//false

 <script>

 var str = "I Love China!!We are Chinese!!"

  //exec()  检索字符串中指定的值。返回找到的值，并确定其位置

  var patt = /[Ch]/;

  console.log(patt.exec(str));//["C", index: 7, input: "I Love China!!We are Chinese!!", groups: undefined]

  var patt2 = /Ch/;

  console.log(patt2.exec(str));//["Ch", index: 7, input: "I Love China!!We are Chinese!!", groups: undefined]

  //字符串中可以使用正则表达式的方法

  // match()    查找找到一个或多个正则表达式的匹配

 console.log(str.match("Ch"));//["Ch", index: 7, input: "I Love China!!We are Chinese!!", groups: undefined]

  console.log(str.match(patt2));//"Ch", index: 7, input: "I Love China!!We are Chinese!!", groups: undefined]

  console.log(str.match(patt));//["C", index: 7, input: "I Love China!!We are Chinese!!", groups: undefined]

  var patt3 = /Ch/g;  //exec方法中修饰符g无效

  console.log(patt3.exec(str));//["Ch", index: 7, input: "I Love China!!We are Chinese!!", groups: undefined]

  console.log(str.match(patt3));//(2) ["Ch", "Ch"]

  // replace() 在字符串中查找匹配的子串， 并替换与正则表达式匹配的子串

  var str = "Hello boys and girls!";

  console.log(str.replace(" ",","));//Hello,boys and girls!

  console.log(str.replace(/\s/,","));//Hello,boys and girls!

  console.log(str.replace(/\s/g,","));//Hello,boys,and,girls!

  // search()   查找与正则表达式相匹配的值  返回第一次出现的索引

  console.log(str.indexOf("o"));//

  console.log(str.indexOf("o",5));//

  console.log(str.search("o"));//4  只有一个参数

  console.log(str.search(/o/));//

  // split()    把字符串分割为字符串数组

  console.log(str.split(" "));//["Hello", "boys", "and", "girls!"]

  console.log(str.split(/\s/));//["Hello", "boys", "and", "girls!"]　

 </script>

 var str = "Hello 中国！！Hello 北京！！";

 // 匹配中文：[\u4e00-\u9fa5]

 // 是一个固定用法，中文只能在正则表达式里这样表示

 var patt = /[\u4e00-\u9fa5]/g;

 // g  global，执行全局匹配

 console.log(str.match(patt));

 // i  忽略大小写

 var patt2 = /[A-Z]/g;

 console.log(str.match(patt2));

 var patt3 = /[A-Z]/gi;

 console.log(str.match(patt3));

 // m 执行多行匹配

 var str2 = "感谢大家光临，本人于\n10月1日上午在家观看国兵直播";

 var patt4 = /^1/g;  //^ 以指定规则开头

 console.log(patt4.test(str2));//false

 var patt5 = /^1/gm;

 console.log(patt5.test(str2));//true

 // [A-z]:查找所有的字母(大小写字母)

 // [0-9A-z]:包含所有的数字和字母(大小写字母)

 var str = "Hello@!~-+=123$%^&*()rrr[]{},.4`56_<>\/\\";

 var patt = /[A-z]/g;

 console.log(str.match(patt));// ["H", "e", "l", "l", "o", "^", "r", "r", "r", "[", "]", "_", "\"]

 var patt2 = /[A-Za-z]/g;

 console.log(str.match(patt2));//(8) ["H", "e", "l", "l", "o", "r", "r", "r"]

 var str = "hello world";

 console.log(str.match(/[hor]/g));//(4) ["h", "o", "o", "r"]

 console.log(str.match(/[^hor]/g));//(7) ["e", "l", "l", " ", "w", "l", "d"]