replace()方法

语法

string.replace(subString|RegExp,string|funcion) 主要用法是：第一个参数为正则，第二个参数为需要替换的值。

replace(string,string)

  1. "this is that issue".replace('is','Is');
  2. // "thIs name issue"

只把第一个is字符串替换成Is。
因为这边没用到正则的全局匹配，所以默认只替换第一个。

关键字使用

  1. "this is that issue".replace('is','$&');
  2. "this is that issue".replace('is','$`');
  3. "this is that issue".replace('is',"$'");
字符 替换文本
$1、$2、…、$99 与 regexp 中的第 1 到第 99 个子表达式相匹配的文本。
$& 与 regexp 相匹配的子串。
$` 位于匹配子串左侧的文本。此处为反引号
$’ 位于匹配子串右侧的文本。此处为单引号

replace(RegExp,string)

  1. "this is that issue".replace(/i\w*s/g,'Is');
  2. // "thIs Is that Isue"

直接把所有符合正则的字符串替换成Is。
其中包括this中的is、is、issue中的is。

  1. "this is that issue".replace(/i(\w*)s/g,'$1');
  2. "this is that issue".replace(/(i)(\w*)s/g,'$2');
  3. "this is that issue".replace(/(i)(\w*)(s)/g,'$3');

replace(string,funcion)

  1. "this is that issue".replace('is',function(){
  2.     console.log(arguments);
  3. });
  4. //  ["is", 2, "this is that issue"]

第一个参数为匹配到的字符串
第二个参数为匹配到的索引
第三个参数为替换前的字符串

replace(RegExp,funcion)

  1. "this is that issue".replace(/i\w*s/g,function(){
  2.     console.log(arguments);
  3. });
  4. //  ["is", 2, "this is that issue"]
  5. //  ["is", 5, "this is that issue"]
  6. //  ["iss", 13, "this is that issue"]

第一个参数为匹配到的字符串
第二个参数为匹配到的索引
第三个参数为替换前的字符串

  1. //正则中包含一个括号
  2. "this is that issue".replace(/i(\w*)s/g,function(){
  3.     console.log(arguments);
  4. });
  5. //  ["is", "", 2, "this is that issue"]
  6. //  ["is", "", 5, "this is that issue"]
  7. //  ["iss", "s", 13, "this is that issue"]
  9. //正则中包含多个括号
  10. "this is that issue".replace(/(i)(\w*)(s)/g,function(){
  11.     console.log(arguments);
  12. });
  13. //  ["is", "i", "", "s", 2, "this is that issue"]
  14. //  ["is", "i", "", "s", 5, "this is that issue"]
  15. //  ["iss", "i", "s", "s", 13, "this is that issue"]

从中可以看出：
第一个参数为匹配到的字符串
中间部分即为各个括号匹配到的子字符串
倒数第二个参数为匹配到的索引
倒数第一个参数为替换前的字符串
即形式为：[正则匹配结果,...[分组匹配结果],索引,原字符串]