js中str.match返回值相关

match方法的匹配结果为一个数组。这个数组分为4部分，依次为:

1. 整个正则表达式匹配的字符串

2. 括号匹配的子串，每一对括号对应一个子串

str = "12324"
str.match(/\d+/)
[ '12324']

str = "12324"
str.match(/(\d+)/)
[ '12324', '12324']

str = "123abc"
 str.match(/\d+[a-z]+/)
[ '1232abc']

str = "1232abc"
str.match(/(\d+)([a-z]+)/)
[ '1232abc', '1232', 'abc']