The problem of obtaining url parameters by JS

problem description 

 url: http://localhost:63343/IPcom/goodsDetail.html?booksId=1
 alter r  booksId=1,,1,
   booksId=1

the environmental background of the problems and what methods you have tried

related codes

/ / Please paste the code text below (do not replace the code with pictures) 

 function getUrlParam(name) {
    var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)"); 
    var r = window.location.search.substr(1).match(reg);  
    alert(r);
    if (r != null) return unescape(r[2]);

    return null; //
}

//URLbooksId
var id = getUrlParam("booksId");
console.log("id:"+id);

what result do you expect? What is the error message actually seen?

Javascript
Aug.16,2021

match where there is a grouping, the first one is matched to, the second, and the third represents the content of the grouping in parentheses in you

the result of this is mainly the problem of the match () method. When it is not a global search after a regular expression

The return value of the

match () method is an array,

The first element in the

array is the matched data, and the subsequent element is the result of the regular expression subexpression matching.

your regular expression has three subexpressions, so there are three elements corresponding to three substrings in the returned array, and the other elements in the array do not answer.

the test code is as follows: 

var reg = new RegExp("(^|&)num=([^&]*)(&|$)");
var url = "num=1";
var r = url.match(reg);  
console.log(r)

result:

for the definition of specific match () methods, please see w3C: http://www.w3school.com.cn/js.

.

Previous: Does anyone know how to use ionic4's ion-menu? can you give me an example?

Next: How to load model on demand when using dva-no-router with next.js?

css mysql arrays josn react html typescript webpack npm sass R objective-c .net sql-server jquery python-3.x angularjs django angular excel regex iphone ajax linux xml pandas vba spring database wordpress string wpf xcode windows bash postgresql oracle multithreading eclipse list firebase algorithm macos forms image scala visual-studio azure bootstrap spring-boot react-native python-2.7 docker performance function winforms matlab powershell apache dataframe api sqlite numpy rest shell selenium flutter dart maven loops qt swing android-studio csv express file class tensorflow sorting codeigniter perl
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1eb8cd1-47446.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1eb8cd1-47446.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?