[英]Regex pattern matching with various end points
我想通過javascript從以下字符串列表中提取具有特定模式的子字符串。
但是我在設置正則表達式模式時遇到了問題。
輸入字符串列表
搜索?w = tot&DA = YZR&t__nil_searchbox = btn&sug =&o =& q=%EB%B9%84%EC%BD%98
搜索? q=%EB%B9%84%EC%BD%98
&go =%EC%A0…4%EB%B9%84%EC%BD%98&sc = 8-2&sp = -1&sk =&cvid = f05407c5bcb9496990d2874135aee8e9
其中= nexearch& query=%EB%B9%84%EC%BD%98
&sm = top_hty&fbm = 0&ie = utf8
預期模式匹配結果
以上情況為%EB%B9%84%EC%BD%98
。
正則表達式
+ /
/(query|q)=.*
+ + /
它的終點是$
或first appeared &
題
? 我應該為寫什么?
您可以在這里進行測試。 謝謝。
將第一個捕獲組轉換為非捕獲組,然后添加一個否定的字符類而不是.*
\b(?:query|q)=([^&\n]*)
> var s = "where=nexearch& query=%EB%B9%84%EC%BD%98&sm=top_hty&fbm=0&ie=utf8"
undefined
> var pat = /\b(?:query|q)=([^&\n]*)/;
> pat.exec(s)[1]
'%EB%B9%84%EC%BD%98'
我個人建議一種替代方法,使用更多過程函數來匹配所需的參數值,而不是“簡單”的正則表達式。 雖然它乍看起來可能比較復雜,但是如果您將來需要查找不同的或附加的參數值,它的確可以輕松擴展。
說:
/* haystack:
String, the string in which you're looking for the
parameter-values,
needles:
Array, the parameters whose values you're looking for
*/
function queryGrab(haystack, needles) {
// creating a regular expression from the array of needles,
// given an array of ['q','query'], this will result in:
// /^(q)|(query)/gi
var reg = new RegExp('^(' + needles.join(')|(') + ')', 'gi'),
// finding either the index of the '?' character in the haystack:
queryIndex = haystack.indexOf('?'),
// getting the substring from the haystack, starting
// after the '?' character:
keyValues = haystack.substring(queryIndex + 1)
// splitting that string on the '&' characters,
// to form an array:
.split('&')
// filtering that array (with Array.prototype.filter()),
// the 'keyValue' argument is the current array-element
// from the array over which we're iterating:
.filter(function(keyValue) {
// if RegExp.prototype.test() returns true,
// meaning the supplied string ('keyValue')
// is matched by the created regular expression,
// the current element is retained in the filtered
// array:
return reg.test(keyValue);
// converting that filtered-array to a string
// on the naive assumption each searched-string
// should return only one match:
}).toString();
// returning a substring of the keyValue, from after
// the position of the '=' character:
return keyValues.substring(keyValues.indexOf('=') + 1);
}
// essentially irrelevant, just for the purposes of
// providing a demonstration; here we get all the
// elements of class="haystack":
var haystacks = document.querySelectorAll('.haystack'),
// the parameters we're looking for:
needles = ['q', 'query'],
// an 'empty' variable for later use:
retrieved;
// using Array.prototype.forEach() to iterate over, and
// perform a function on, each of the .haystack elements
// (using Function.prototype.call() to use the array-like
// NodeList instead of an array):
Array.prototype.forEach.call(haystacks, function(stack) {
// like filter(), the variable is the current array-element
// retrieved caches the found parameter-value (using
// a variable because we're using it twice):
retrieved = queryGrab(stack.textContent, needles);
// setting the next-sibling's text:
stack.nextSibling.nodeValue = '(found: ' + retrieved + ')';
// updating the HTML of the current node, to allow for
// highlighting:
stack.innerHTML = stack.textContent.replace(retrieved, '<span class="found">$&</span>');
});
function queryGrab(haystack, needles) { var reg = new RegExp('^(' + needles.join(')|(') + ')', 'gi'), queryIndex = haystack.indexOf('?'), keyValues = haystack.substring(queryIndex + 1) .split('&') .filter(function(keyValue) { return reg.test(keyValue); }).toString(); return keyValues.substring(keyValues.indexOf('=') + 1); } var haystacks = document.querySelectorAll('.haystack'), needles = ['q', 'query'], retrieved; Array.prototype.forEach.call(haystacks, function(stack) { retrieved = queryGrab(stack.textContent, needles); stack.nextSibling.nodeValue = '(found: ' + retrieved + ')'; stack.innerHTML = stack.textContent.replace(retrieved, '<span class="found">$&</span>'); });
ul { margin: 0; padding: 0; } li { margin: 0 0 0.5em 0; padding-bottom: 0.5em; border-bottom: 1px solid #ccc; list-style-type: none; width: 100%; } .haystack { display: block; color: #999; } .found { color: #f90; }
<ul> <li><span class="haystack">search?w=tot&DA=YZR&t__nil_searchbox=btn&sug=&o=&q=%EB%B9%84%EC%BD%98</span> </li> <li><span class="haystack">search?q=%EB%B9%84%EC%BD%98&go=%EC%A0…4%EB%B9%84%EC%BD%98&sc=8-2&sp=-1&sk=&cvid=f05407c5bcb9496990d2874135aee8e9</span> </li> <li><span class="haystack">where=nexearch&query=%EB%B9%84%EC%BD%98&sm=top_hty&fbm=0&ie=utf8</span> </li> </ul>
參考文獻:
正則表達式不是解析這些查詢字符串的最佳方法。 有庫和工具,但是如果您想自己做:
function parseQueryString(url) {
return _.object(url . // build an object from pairs
split('?')[1] . // take the part after the ?
split('&') . // split it by &
map(function(str) { // turn parts into 2-elt array
return str.split('='); // broken at =
})
);
}
這使用了_.object
的_.object
,它通過鍵/值對的數組數組創建對象,但是如果您不想使用它,則可以用兩行代碼編寫自己的對象。
現在,您正在尋找的價值僅僅是
params = parseQueryString(url);
return params.q || params.query;
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