如何使用JavaScript获取文件扩展名？
见代码：如何使用JavaScript获取文件扩展名？,javascript,file-extension,Javascript,File Extension,见代码： var file1 = "50.xsl"; var file2 = "30.doc"; getFileExtension(file1); //returns xsl getFileExtension(file2); //returns doc function getFileExtension(filename) { /*TODO*/ } 编辑：奇怪的是（也许不是），replace方法第二个参数中的$1似乎不起作用。。。抱歉。更新的编辑：自从这个问题最初发布以来，很多事情都
var file1 = "50.xsl";
var file2 = "30.doc";
getFileExtension(file1); //returns xsl
getFileExtension(file2); //returns doc
function getFileExtension(filename) {
/*TODO*/
}
编辑：奇怪的是（也许不是），replace方法第二个参数中的
$1编辑：因为这是公认的答案；确实好得多：
return filename.split('.').pop();
我以前的回答是：
return /[^.]+$/.exec(filename);
return (/[.]/.exec(filename)) ? /[^.]+$/.exec(filename) : undefined;
"a.b" (=> "b")
"a" (=> "")
".hidden" (=> "")
"" (=> "")
null (=> "")
我刚刚意识到，仅仅对p4bl0的答案发表评论是不够的，尽管Tom的答案显然解决了问题：
return filename.replace(/^.*?\.([a-zA-Z0-9]+)$/, "$1");
return filename.substring(filename.lastIndexOf('.')+1, filename.length) || filename;
.htaccess”var a = filename.split(".");
if( a.length === 1 || ( a[0] === "" && a.length === 2 ) ) {
return "";
}
return a.pop(); // feel free to tack .toLowerCase() here if you want
a.lengtha[0]==”a.length==2希望这有助于解决稍微复杂一些的问题。就性能而言，我认为这种解决方案适用于大多数浏览器。但是，对于大多数常见用途，此代码应该是完全可用的。对于大多数应用程序，一个简单的脚本，如
return /[^.]+$/.exec(filename);
image.jpg?foo=bar
var trueFileName = parse_url('image.jpg?foo=bar').file;
function getFileExtension(filename) {
var fileinput = document.getElementById(filename);
if (!fileinput)
return "";
var filename = fileinput.value;
if (filename.length == 0)
return "";
var dot = filename.lastIndexOf(".");
if (dot == -1)
return "";
var extension = filename.substr(dot, filename.length);
return extension;
}
以下解决方案足够快且短，可用于批量操作并节省额外字节：
return fname.slice((fname.lastIndexOf(".") - 1 >>> 0) + 2);
return fname.slice((Math.max(0, fname.lastIndexOf(".")) || Infinity) + 1);
“fname-1-10“name”“.htaccess”>>-14294967295-24294967294“”如果您想要以相同方式工作的更清晰的解决方案（加上对完整路径的额外支持），请检查以下扩展版本。此解决方案将比以前的一行程序慢，但更容易理解
function getExtension(path) {
var basename = path.split(/[\\/]/).pop(), // extract file name from full path ...
// (supports `\\` and `/` separators)
pos = basename.lastIndexOf("."); // get last position of `.`
if (basename === "" || pos < 1) // if file name is empty or ...
return ""; // `.` not found (-1) or comes first (0)
return basename.slice(pos + 1); // extract extension ignoring `.`
}
console.log( getExtension("/path/to/file.ext") );
// >> "ext"
函数getExtension（路径）{
var basename=path.split（/[\\/]）.pop（），//从完整路径提取文件名。。。
//（支持“\\”和“/”分隔符）
pos=basename.lastIndexOf（“.”；//获取“”的最后位置`
if（basename==“”| | pos<1）//如果文件名为空或。。。
返回“”；//`.`未找到（-1）或先到（0）
返回basename.slice（pos+1）；//提取扩展名忽略``
}
log（getExtension（“/path/to/file.ext”）；
//>>“分机”
这三种变体都可以在客户端的任何web浏览器中使用，也可以在服务器端的NodeJS代码中使用。Wallacer的回答很好，但还需要再检查一次 若文件并没有扩展名，它将使用文件名作为扩展名，这是不好的 试试这个：
return ( filename.indexOf('.') > 0 ) ? filename.split('.').pop().toLowerCase() : 'undefined';
不要忘记某些文件可能没有扩展名，因此：
var parts = filename.split('.');
return (parts.length > 1) ? parts.pop() : '';
快速，可正确使用路径
(filename.match(/[^\\\/]\.([^.\\\/]+)$/) || [null]).pop()
/path/.htaccess => null
/dir.with.dot/file => null
使用split的解决方案速度较慢，使用lastIndexOf的解决方案无法处理边缘情况。我只是想与大家分享一下
fileName.slice(fileName.lastIndexOf('.'))
function getExtention(fileName){
var i = fileName.lastIndexOf('.');
if(i === -1 ) return false;
return fileName.slice(i)
}
如果要查找特定的扩展名并知道其长度，可以使用substr：
var file1 = "50.xsl";
if (file1.substr(-4) == '.xsl') {
// do something
}
JavaScript参考：我在派对上迟到了很多个月，但为了简单起见，我使用了类似的方法
var fileName=“I.Am.fileName.docx”；
var nameLen=fileName.length；
var lastDotPos
return fname.slice((fname.lastIndexOf(".") - 1 >>> 0) + 2);
return fname.slice((Math.max(0, fname.lastIndexOf(".")) || Infinity) + 1);
"" --> ""
"name" --> ""
"name.txt" --> "txt"
".htpasswd" --> ""
"name.with.many.dots.myext" --> "myext"
function getExtension(path) {
var basename = path.split(/[\\/]/).pop(), // extract file name from full path ...
// (supports `\\` and `/` separators)
pos = basename.lastIndexOf("."); // get last position of `.`
if (basename === "" || pos < 1) // if file name is empty or ...
return ""; // `.` not found (-1) or comes first (0)
return basename.slice(pos + 1); // extract extension ignoring `.`
}
console.log( getExtension("/path/to/file.ext") );
// >> "ext"
return ( filename.indexOf('.') > 0 ) ? filename.split('.').pop().toLowerCase() : 'undefined';
var parts = filename.split('.');
return (parts.length > 1) ? parts.pop() : '';
(filename.match(/[^\\\/]\.([^.\\\/]+)$/) || [null]).pop()
/path/.htaccess => null
/dir.with.dot/file => null
fileName.slice(fileName.lastIndexOf('.'))
function getExtention(fileName){
var i = fileName.lastIndexOf('.');
if(i === -1 ) return false;
return fileName.slice(i)
}
var file1 = "50.xsl";
if (file1.substr(-4) == '.xsl') {
// do something
}
string.match(/(.*)\??/i).shift().replace(/\?.*/, '').split('.').pop()
// Example
// some.url.com/with.in/&ot.s/files/file.jpg?spec=1&.ext=jpg
// jpg
var file = "hello.txt";
var ext = (function(file, lio) {
return lio === -1 ? undefined : file.substring(lio+1);
})(file, file.lastIndexOf("."));
// hello.txt -> txt
// hello.dolly.txt -> txt
// hello -> undefined
// .hello -> hello
/**
* Extract file extension from URL.
* @param {String} url
* @returns {String} File extension or empty string if no extension is present.
*/
var getFileExtension = function (url) {
"use strict";
if (url === null) {
return "";
}
var index = url.lastIndexOf("/");
if (index !== -1) {
url = url.substring(index + 1); // Keep path without its segments
}
index = url.indexOf("?");
if (index !== -1) {
url = url.substring(0, index); // Remove query
}
index = url.indexOf("#");
if (index !== -1) {
url = url.substring(0, index); // Remove fragment
}
index = url.lastIndexOf(".");
return index !== -1
? url.substring(index + 1) // Only keep file extension
: ""; // No extension found
};
"https://www.example.com:8080/segment1/segment2/page.html?foo=bar#fragment" --> "html"
"https://www.example.com:8080/segment1/segment2/page.html#fragment" --> "html"
"https://www.example.com:8080/segment1/segment2/.htaccess?foo=bar#fragment" --> "htaccess"
"https://www.example.com:8080/segment1/segment2/page?foo=bar#fragment" --> ""
"https://www.example.com:8080/segment1/segment2/?foo=bar#fragment" --> ""
"" --> ""
null --> ""
"a.b.c.d" --> "d"
".a.b" --> "b"
".a.b." --> ""
"a...b" --> "b"
"..." --> ""
function extension(filename) {
var r = /.+\.(.+)$/.exec(filename);
return r ? r[1] : null;
}
function getFileExtension(fileNameOrURL, showUnixDotFiles)
{
/* First, let's declare some preliminary variables we'll need later on. */
var fileName;
var fileExt;
/* Now we'll create a hidden anchor ('a') element (Note: No need to append this element to the document). */
var hiddenLink = document.createElement('a');
/* Just for fun, we'll add a CSS attribute of [ style.display = "none" ]. Remember: You can never be too sure! */
hiddenLink.style.display = "none";
/* Set the 'href' attribute of the hidden link we just created, to the 'fileNameOrURL' argument received by this function. */
hiddenLink.setAttribute('href', fileNameOrURL);
/* Now, let's take advantage of the browser's built-in parser, to remove elements from the original 'fileNameOrURL' argument received by this function, without actually modifying our newly created hidden 'anchor' element.*/
fileNameOrURL = fileNameOrURL.replace(hiddenLink.protocol, ""); /* First, let's strip out the protocol, if there is one. */
fileNameOrURL = fileNameOrURL.replace(hiddenLink.hostname, ""); /* Now, we'll strip out the host-name (i.e. domain-name) if there is one. */
fileNameOrURL = fileNameOrURL.replace(":" + hiddenLink.port, ""); /* Now finally, we'll strip out the port number, if there is one (Kinda overkill though ;-)). */
/* Now, we're ready to finish processing the 'fileNameOrURL' variable by removing unnecessary parts, to isolate the file name. */
/* Operations for working with [relative, root-relative, and absolute] URL's ONLY [BEGIN] */
/* Break the possible URL at the [ '?' ] and take first part, to shave of the entire query string ( everything after the '?'), if it exist. */
fileNameOrURL = fileNameOrURL.split('?')[0];
/* Sometimes URL's don't have query's, but DO have a fragment [ # ](i.e 'reference anchor'), so we should also do the same for the fragment tag [ # ]. */
fileNameOrURL = fileNameOrURL.split('#')[0];
/* Now that we have just the URL 'ALONE', Let's remove everything to the last slash in URL, to isolate the file name. */
fileNameOrURL = fileNameOrURL.substr(1 + fileNameOrURL.lastIndexOf("/"));
/* Operations for working with [relative, root-relative, and absolute] URL's ONLY [END] */
/* Now, 'fileNameOrURL' should just be 'fileName' */
fileName = fileNameOrURL;
/* Now, we check if we should show UNIX dot-files, or not. This should be either 'true' or 'false'. */
if ( showUnixDotFiles == false )
{
/* If not ('false'), we should check if the filename starts with a period (indicating it's a UNIX dot-file). */
if ( fileName.startsWith(".") )
{
/* If so, we return a blank string to the function caller. Our job here, is done! */
return "";
};
};
/* Now, let's get everything after the period in the filename (i.e. the correct 'file extension'). */
fileExt = fileName.substr(1 + fileName.lastIndexOf("."));
/* Now that we've discovered the correct file extension, let's return it to the function caller. */
return fileExt;
};
function getExt(filepath){
return filepath.split("?")[0].split("#")[0].split('.').pop();
}
getExt("../js/logic.v2.min.js") // js
getExt("http://example.net/site/page.php?id=16548") // php
getExt("http://example.net/site/page.html#welcome.to.me") // html
getExt("c:\\logs\\yesterday.log"); // log
import path from 'path';
console.log(path.extname('abc.txt'));
path.extname('abc.txt').slice(1) // 'txt'
path.extname('abc') // ''