在javascript语言精粹 看到url的正则，将其记录下来
var parse_url = /^(?:([A-Za-z]+):)?(\/{0,3})([0-9.\-A-Za-z]+)(?::(\d+))?(?:\/([^?#]*))?(?:\?([^#]*))?(?:#(.*))?$/;
var url = "http://www.ora.com:80/goodparts?q#fragment";
执行 具体代码见下述：
var url = "http://www.ora.com:80/goodparts?q#fragment";
var parse_url = /^(?:([A-Za-z]+):)?(\/{0,3})([0-9.\-A-Za-z]+)(?::(\d+))?(?:\/([^?#]*))?(?:\?([^#]*))?(?:#(.*))?$/;
var result = parse_url.exec(url);
var names = [‘url‘,‘scheme‘,‘slash‘,‘host‘,‘port‘,‘path‘,‘query‘,‘hash‘];
var blanks = ‘ ‘;
var i;
for (i = 0; i < names.length; i += 1){
document.writeln(names[i] + ‘:‘ + blanks.substring(names[i].length), result[i]);
}
执行结果：
url: http://www.ora.com:80/goodparts?q#fragment
scheme: http
slash: //
host: www.ora.com
port: 80
path: goodparts
query: q
hash: fragment
关于上述url的正则的部分解释：
/^(?:([A-Za-z]+):)?(\/{0,3})([0-9.\-A-Za-z]+)(?::(\d+))?(?:\/([^?#]*))?(?:\?([^#]*))?(?:#(.*))?$/
1.^表示开始 $表示结尾
/^(?:([A-Za-z]+):)?(\/{0,3})([0-9.\-A-Za-z]+)(?::(\d+))?(?:\/([^?#]*))?(?:\?([^#]*))?(?:#(.*))?$/
2. (?:pattern) 表示匹配pattern但不获取匹配结果
(?:([A-Za-z]+):) 则表示匹配 ([A-Za-z]+): ，但只返回匹配到的([A-Za-z]+)的结果，并不返回：
/^(?:([A-Za-z]+):)?(\/{0,3})([0-9.\-A-Za-z]+)(?::(\d+))?(?:\/([^?#]*))?(?:\?([^#]*))?(?:#(.*))?$/
3. \*{3},因为*是特殊字符，所以用转义字符，该表达式表示匹配3个*，即***
同理\/{0,3}表示匹配0到3个/,即没有/或者/, //, ///
/^(?:([A-Za-z]+):)?(\/{0,3})([0-9.\-A-Za-z]+)(?::(\d+))?(?:\/([^?#]*))?(?:\?([^#]*))?(?:#(.*))?$/
4. 方括号中的^表示 非 的意思
[^?#] 则表示 非 ？ 且 非 # 的其他字符
/^(?:([A-Za-z]+):)?(\/{0,3})([0-9.\-A-Za-z]+)(?::(\d+))?(?:\/([^?#]*))?(?:\?([^#]*))?(?:#(.*))?$/
* 匹配前一项0次或多次。即{0，}
？匹配前一项0次或1次。即{0,1}