/^(?:\/(?=$))?$/this rule is used to match the
of an empty string."".match(/^(?:\/(?=$))?$/)
["", index: 0, input: "", groups: undefined]
"1".match(/^(?:\/(?=$))?$/)
null? = I know this is an antecedent assertion, which means that it must be followed by $.
but I don"t understand how the whole regular match is empty. (? = $) it has been defined that it must be followed by $, so if there is at least $, how can it be empty?
matches a blank row or data with only / in a row
such as:
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(? =) will be used as a matching check, but will not appear in the matching result string
(?:) is used as a match check and appears in the matching result character. It differs from (.) in that it is not returned as a child match.
var data = 'windows 98 is ok';
data.match(/windows (?=\d+)/); // ["windows "]
data.match(/windows (?:\d+)/); // ["windows 98"]
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1. The string str= "zz=aaa,bb=bbb,cc=ccc;User=ZZZ&zz=aaa1&bb=bbb1&cc=ccc1 " 2. To implement, for example, I pass in the parameter zz, and find the value of aaa1 in the zz=aaa1 after User=ZZZ. How to write the corresponding rule? ...
^ (18 [0-9] {9}) | (15 [0-9] {9}) $ Why the rule matches 1844444444444444 . My understanding of this rule is starting with 18 or 15 followed by 9 digits 0-9 . Note: I know there are other ways to write the rules of mobile phone numbers. I just ...
The range of characters is text, letters, numbers and "( ", ") ", "[ ", "] ", "space "; how should the rule of up to 20 words be written ...
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1. The string in the cookie fetched by the foreground is a connection of multiple cookie, for example, these two types: var str = "OnlineCookie=OnlineCookie&UserType=11111111111111111&UID=39&UserName=; UID=; UserType=; UserName=";...
MEDU1778421 FEJ7296886 FCIU2741867 FEJ7296887 GLDU9472098 FEJ7296888 I want to match the following numbers and replace them with spaces for example, how to match letters and spaces MEDU1778421 FCIU2741867 GLDU9472098 ...
as shown in the figure: I use str.replace ( (null) , "jsonCallBack "); can only replace the first null, , but what should I do to replace the third? the following is the string "< input type= " radio "name= " p_date_type_sl_sl_sl "value= " i...
var newsname; ctrl.checkNameLegal = function () { if (ctrl.fileName) { var exports = ^(?![.])[ u4e00- u9fa5_.a-zA-Z0-9]+$ ig; if (exports.test(ctrl.fileName)) { newsname = ctrl.fileName; } else { ctrl.fileName = newsname; } } else { newsname = ...
when trying to use regular matching 12-128, it is found that it can match to 129, such as the question. 192.168.0.(12[0-8]|1[0-1][0-9]|[2-9][0-9]|1[2-9]) True is returned when matches 129. judgment 255 will also match the first two digits 25. h...
1. Requirements: write a regular 2 that can automatically add a space for every 4 digits written. Problem: the regular (or incorrect) is written out, but the spaces cannot be deleted! 3. Picture 4. Code innput listening: `$("ul.information-...
const datas =[ "https: img.codeshelper.com upload img 2021 03 09 1tcsu5c0vun5800.png", "https: img.codeshelper.com upload img 2021 03 09 mc3p5hxjed25801.png", "https: img.codeshelper.com upload img 2021 03 09 b0sxs...
*start* import aaa ; *end* let a={ b: c *start* d: e *end* } now you want to match all the content from * start* to * end* , and replace it with ", , that is, all that s left in the above code is: . let a={ b:...
A HTML in a text box contains text and img tags for example <img src=".. .. static images express 4.gif" alt="[em_4]"><img src=".. .. static images express 4.gif" alt="[em_4]"> make Filter look like...
the following regular expression can successfully configure key, (^ |) in url. Doesn t it mean start or empty? how can it match & what s wrong with it? regular ?ie=utf-8&f=8&rsv_bp=0&rsv_idx=1&tn=baidu&wd=%E6%AD%A3%E5%88%99%E8%A1...
as shown in the figure above: in the first way, the $3.23 is identified as false , but in the second way, only one parameter g is removed and passed. According to principle, the first one should also be passed, please give us guidance! ...
example: (999 < video > < video > ) I want to delete the p tag in parentheses (). ...
find the underscore through the regular expression, return the previous content, and don t want anything else. ...
password requires 1, number 2, letter 3, number + letter ...
Code first: if( ( module (?:.+[^ .html])) .test(". src module comment details.html")){ console.log(RegExp.$1) module comment details } if( ( module (?:.+[^ .js])) .test(". src module comment details.js")){ console...
for example: abdsdsdfsdf1526614206112164350fskdfskdf1526614199681037404bcmvbcvbmcnvz: match 1526614206112164350 and 1526614199681037404 in the string, add quotation marks on both sides, and process it as follows: abdsdsdfsdf "1526614206112164350 " fskdf...