Question

    var keys = {};
    source.replace(
            /([^=&]+)=([^&]*)/g,
            function(full, key, value) {
                keys[key] =
                        (keys[key] ? keys[key] + "," : "") + value;
                return "";
            }
    );
    var result = [];
    for (var key in keys) {
        result.push(key + "=" + keys[key]);
    }
    return result.join("&");
    }
    alert(compress("foo=1&foo=2&blah=a&blah=b&foo=3"));

我仍然混淆这个/（[^ =＆amp;] +）=（[^＆amp;] *）/ g，+和*用于？

Answer 1

^表示不是这些，+表示一个或多个匹配的字符，（）表示组。 *是任何匹配的数量（0 +）。

http://www.cheatography.com/davechild/cheat-sheets/regular-expressions/

因此，通过观察它，我猜它取代了任何不是=＆amp; =＆amp;或＆amp; =＆amp;或==，这很奇怪。

Answer 2

+和*被称为量词。它们确定子集匹配的次数（紧接在它们之前的字符集通常与量词所适用的[]或()重叠）重复。

/     start of regex

 (    group 1 starts
   [^ anything that does not match
   =& equals or ampersand
   ]+ one or more of above
 )    group 1 ends

   =  followed by equals sign followed by

 (    group 2 starts
   [^ anything that does not match
   =& ampersand
   ]* zero or more of above
 )    group 2 ends

/     end of regex

理解这个正则表达式

2 个答案: