Javascript JS：从字符串中的路径中删除文件名的最优化方法？
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JS: Most optimized way to remove a filename from a path in a string?
提问by DaVince
I have strings formatted as follows:
path/to/a/filename.txt
我的字符串格式如下：
path/to/a/filename.txt
Now I'd like to do some string manipulation which allows me to very efficiently remove the "filename.txt" part from this code. In other words, I want my string to become this:
path/to/a/
现在我想做一些字符串操作，这使我能够非常有效地从此代码中删除“filename.txt”部分。换句话说，我希望我的字符串变成这样：
path/to/a/
What's the most efficient way to do this? Currently I'm splitting the string and reconnecting the seperate elements except for the last one, but I get the feeling this is a really, REALLY inefficient way to do it. Here's my current, inefficient code:
执行此操作的最有效方法是什么？目前我正在拆分字符串并重新连接除最后一个之外的单独元素，但我觉得这是一种非常非常低效的方法。这是我当前的低效代码：
res.getPath = function(file)
{
var elem = file.split("/");
var str = "";
for (var i = 0; i < elem.length-1; i++)
str += elem[i] + "/";
return str;
}
回答by Kees de Kooter
Use lastIndexOf() to find the position of the last slash and get the part before the slash with substring().
使用 lastIndexOf() 查找最后一个斜杠的位置，并使用 substring() 获取斜杠之前的部分。
str.substring(0, str.lastIndexOf("/"));
回答by Gumbo
How about this:
这个怎么样：
"path/to/a/filename.txt".split("/").slice(0, -1).join("/")+"/"
回答by Richie Bendall
If you're using Node.js:
如果您使用的是 Node.js：
const path = require("path")
const removeFilePart = dirname => path.parse(dirname).dir
removeFilePart("/a/b/c/d.txt")
// Returns "/a/b/c"
回答by shiva2492
str = str.split('/')
str.pop()
str.join('/') + '/'
回答by Pointy
function splitPath(path) {
var dirPart, filePart;
path.replace(/^(.*\/)?([^/]*)$/, function(_, dir, file) {
dirPart = dir; filePart = file;
});
return { dirPart: dirPart, filePart: filePart };
}
there that's better
那里更好
回答by Grodriguez
If this is to process a filename from a file upload form, the HTML5 spec recommends the following code:
如果要处理来自文件上传表单的文件名，HTML5 规范建议使用以下代码：
function extractFilename(path) {
if (path.substr(0, 12) == "C:\fakepath\")
return path.substr(12); // modern browser
var x;
x = path.lastIndexOf('/');
if (x >= 0) // Unix-based path
return path.substr(x+1);
x = path.lastIndexOf('\');
if (x >= 0) // Windows-based path
return path.substr(x+1);
return path; // just the filename
}
Reference: http://www.w3.org/TR/html5/number-state.html#file-upload-statehttp://www.w3.org/TR/html5/forms.html#file-upload-state-(type=file)
参考：http: //www.w3.org/TR/html5/number-state.html#file-upload-statehttp://www.w3.org/TR/html5/forms.html#file-upload-state -（类型=文件）
回答by André Fiedler
function getDirname(pathname, separator) {
var parts = pathname.split(separator);
if (parts[parts.length - 1].indexOf('.') > -1) {
return parts.slice(0, -1).join(separator)
}
return pathname;
}
Usage:
用法：
var dir = getDirname(url.parse(request.url).pathname, '/');
.
.
var dir = getDirname(path.join('foo', 'bar', 'text.txt'), path.sep);
回答by Юрий Светлов
test/dir/lib/file- _09.ege.jpg- Will be to- test/dir/lib/
test/dir/lib/file- _09.ege.jpg-将会-test/dir/lib/
file- _09.ege.jpg- Will be to- file- _09.ege.jpg
file- _09.ege.jpg-将会-file- _09.ege.jpg
console.log("test - "+getPath('test/dir/lib/file- _09.ege.jpg'));
function getPath(path){
path = path.match(/(^.*[\\/]|^[^\\/].*)/i);
if(path != null){
return path[0];
}else{
return false;
}
}
console.log("test - "+getPath('test/dir/lib/file- _09.ege.jpg'));
function getPath(path){
path = path.match(/(^.*[\\/]|^[^\\/].*)/i);
if(path != null){
return path[0];
}else{
return false;
}
}