[英]JS: Most optimized way to remove a filename from a path in a string?
I have strings formatted as follows: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.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。 In other words, I want my string to become this:
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?执行此操作的最有效方法是什么? 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.
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。 Here's my current, inefficient code:
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;
}
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("/"));
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"
这个怎么样:
"path/to/a/filename.txt".split("/").slice(0, -1).join("/")+"/"
In node, you can use path.dirname
在节点中,您可以使用
path.dirname
const path = require('path')
fullFilePath = '/some/given/path/to-a-file.txt'
directoryPath = path.dirname(fullFilePath)
console.log(directoryPath) // ===> '/some/given/path'
If this is to process a filename from a file upload form, the HTML5 spec recommends the following code:如果这是从文件上传表单处理文件名,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-state
http://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-state
http://www.w3.org/TR/html5/forms.html#file-upload-state -(类型=文件)
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
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);
test/dir/lib/file- _09.ege.jpg
- Will be to - test/dir/lib/
test/dir/lib/file- _09.ege.jpg
-将- test/dir/lib/
file- _09.ege.jpg
- Will be to - file- _09.ege.jpg
file- _09.ege.jpg
- file- _09.ege.jpg
-将到- file- _09.ege.jpg
- 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; } }
str = str.split('/')
str.pop()
str.join('/') + '/'
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