Javascript regex for matching/extracting file extension

Question

The following regex

var patt1=/[0-9a-z]+$/i;

extracts the file extension of strings such as

filename-jpg
filename#gif
fil         


        

Answer 1

Example list:

var fileExtensionPattern = /\.([0-9a-z]+)(?=[?#])|(\.)(?:[\w]+)$/gmi
//regex flags -- Global, Multiline, Insensitive

var ma1 = 'css/global.css?v=1.2'.match(fileExtensionPattern)[0];
console.log(ma1);
// returns .css

var ma2 = 'index.html?a=param'.match(fileExtensionPattern)[0];
console.log(ma2);
// returns .html

var ma3 = 'default.aspx?'.match(fileExtensionPattern)[0];
console.log(ma3);
// returns .aspx

var ma4 = 'pages.jsp#firstTab'.match(fileExtensionPattern)[0];
console.log(ma4);
// returns .jsp

var ma5 = 'jquery.min.js'.match(fileExtensionPattern)[0];
console.log(ma5);
// returns .js

var ma6 = 'file.123'.match(fileExtensionPattern)[0];
console.log(ma6);
// returns .123

Test page.