JS access to local files and directories method (recommended) _javascript tips

JavaScript is a Web page production can not be separated from the scripting language, relying on it, a Web page content is lively, full of vitality. But maybe you haven't found and applied some of its more advanced features? For example, files and folders to read, write and delete, as in VB, VC and other high-level languages often do the same job. How about, do you need to know this knowledge? Then follow me. This article describes in detail how to use the JavaScript language for file operations.

First, the function realizes the core: FileSystemObject object

In fact, to implement the file operation function in JavaScript, the main thing is to rely on the FileSystemObject object. Before detailing the use details of each of the properties and methods of the FileSystemObject object, let's take a look at what related objects and collections This object includes:

Ii. FileSystemObject Programming Trilogy

Programming with a FileSystemObject object is simple, typically through the following steps: Creating FileSystemObject objects, applying related methods, and accessing object-related properties.

(i) Creating FileSystemObject objects

The code to create the FileSystemObject object takes only 1 lines:

var fso = new ActiveXObject ("Scripting.FileSystemObject"); 

After the above code executes, the FSO becomes a FileSystemObject object instance.

(ii) Application of relevant methodologies

After you create an object instance, you can use the associated methods of the object. For example, use the CreateTextFile method to create a text file:

var fso = new ActiveXObject ("Scripting.FileSystemObject"); 

var f1 = fso.createtextfile ("C:\\myjstest.txt", true); 

(iii) Access to object-related properties

To access the related properties of an object, you first establish a handle to the object, which is done by the Get series method: Getdrive is responsible for obtaining the drive information, GetFolder is responsible for obtaining the folder information, GetFile is responsible for obtaining the file information. For example, after pointing to the following code, F1 becomes a handle to the file C:\test.txt:

var fso = new ActiveXObject ("Scripting.FileSystemObject"); 

var f1 = fso. GetFile ("C:\\myjstest.txt"); 

Then, use F1 to access the associated properties of the object. Like what:

var fso = new ActiveXObject ("Scripting.FileSystemObject"); 

var f1 = fso. GetFile ("C:\\myjstest.txt"); 

Alert ("File Last modified:" + F1.) DateLastModified); 

After the last sentence is executed, the last modified Date attribute value for C:\myjstest.txt is displayed.

But one thing. Note: For objects created using the Create method, you do not have to use the Get method to obtain the object handle, and then the handle name created directly by using the Create method can be:

var fso = new ActiveXObject ("Scripting.FileSystemObject"); 

var f1 = fso.createtextfile ("C:\\myjstest.txt", true); 

Alert ("File Last modified:" + F1.) DateLastModified); 

Third, the operation of the driver (drives)

Using the FileSystemObject object to programmatically manipulate drives (drives) and folders (Folders) is easy, like interacting with files in a Windows file browser, such as copying, moving folders, and getting the properties of a folder.

A Drives Object Properties

The drive object is responsible for collecting the contents of the physical or logical drive resource in the system, which has the following properties:

L TotalSize: The drive size in bytes (byte).

L availablespace or FreeSpace: drive free space calculated in bytes (byte).

L DriveLetter: drive letter.

L DriveType: Drive type, value is: removable (mobile media), fixed (fixed media), Network (network Resource), CD-ROM, or RAM disk.

L SerialNumber: Serial code for the drive.

L FileSystem: The file system type of the drive on which the value is fat, FAT32, and NTFS.

L IsReady: The drive is available.

L ShareName: share name.

L VolumeName: Volume label name.

L Path and RootFolder: The path of the drive or the name of the root directory.

Two Drive object Operation routines

The following routines show information such as the volume label, Total capacity, and free space of drive C:

var fso, DRV, s = ""; 

FSO = new ActiveXObject ("Scripting.FileSystemObject"); 

DRV = FSO. Getdrive (FSO. GetDriveName ("c:\\")); 

S + + "Drive C:" + "-"; 

S + + DRV. VolumeName + "\ n"; 

S + + "total space:" + DRV. totalsize/1024; 

S + + "Kb" + "\ n"; 

s + + "free space:" + DRV. freespace/1024; 

S + + "Kb" + "\ n"; 

Iv. Operation folder (Folders)

Actions that involve folders include creating, moving, deleting, and getting related properties.

A List of related properties and methods for the folder object

Two Folder object Operation routines

The following routines practice getting the parent folder name, creating a folder, deleting a folder, and determining whether it is a root directory, and so on:

var fso, fldr, S = ""; 

Create FileSystemObject object instance 

FSO = new ActiveXObject ("Scripting.FileSystemObject"); 

Gets the Drive object 

Fldr = fso. GetFolder ("c:\\"); 

Displays the parent directory name 

alert ("Parent folder name is:" + Fldr + "\ n"); 

Displays the drive name 

alert ("contained on drive" + Fldr). Drive + "\ n"); 

Determines whether the root 

if (fldr. IsRootFolder) 

alert ("This is the root folder."); 

else 

alert ("This folder isn ' t a root folder."); 

Alert ("\ n \ nthe"); 

Create a new folder 

FSO. CreateFolder ("C:\\bogus"); 

Alert ("Created folder C:\\bogus" + "\ n"); 

Displays the folder base name without the path name 

alert ("Basename =" + FSO). Getbasename ("C:\\bogus") + "\ n"); 

Delete the created folder 

FSO. DeleteFolder ("C:\\bogus"); 

V. Operating documents (FILES)

Operations on files are more complex than the drives (Drive) and folders (folder) described above, and are essentially grouped into the following two categories: creation, copying, movement, deletion, and creation, addition, deletion, and reading of file content. The details are detailed below.

(i) Create a file

There are 3 ways to create an empty text file, which is sometimes called a text stream.

The first is the use of the CreateTextFile method. The code is as follows:

var fso, F1; 

FSO = new ActiveXObject ("Scripting.FileSystemObject"); 

F1 = fso. CreateTextFile ("C:\\testfile.txt", true); 

The second is to use the OpenTextFile method and add the ForWriting property, the ForWriting value is 2.

The code is as follows:

var fso, TS; 

var forwriting= 2; 

FSO = new ActiveXObject ("Scripting.FileSystemObject"); 

TS = fso. OpenTextFile ("C:\\Test.txt", ForWriting, True); 

The third is to use the OpenAsTextStream method, also set the ForWriting property. The code is as follows:

Var fso, F1, TS; 

var forwriting = 2; 

FSO = new ActiveXObject ("Scripting.FileSystemObject"); 

Fso. CreateTextFile ("C:\\test1.txt"); 

F1 = fso. GetFile ("C:\\test1.txt"); 

TS = F1. OpenAsTextStream (ForWriting, true); 

(ii) Adding data to documents

When a file is created, you typically add data to a file by following the steps of "Open file-> fill data-> close file."

You can open a file by using the OpenTextFile method of the FileSystemObject object, or by using the OpenAsTextStream method of the file object.

Fill in the data to use the Write, WriteLine, or WriteBlankLines method of the TextStream object. The difference between these 3 is that the Write method does not add a new line break at the end of the write data, the WriteLine method adds a new newline character at the end, and WriteBlankLines adds one or more blank rows.

You can use the Close method of the TextStream object by closing the file.

(iii) Create files and add data routines

The following code combines several steps to create a file, add data, and close a file:

var fso, TF; 

FSO = new ActiveXObject ("Scripting.FileSystemObject"); 

Create new file 

tf = fso. CreateTextFile ("C:\\testfile.txt", true); 

Fill in the data and add the newline character 

TF. WriteLine ("Testing 1, 2, 3."); 

Add 3 empty line 

TF. WriteBlankLines (3); 

Fill in a line without the newline character 

TF. Write ("This is a test."); 

Close File 

(iv) Read the contents of the file

Reading data from a text file uses the read, ReadLine, or ReadAll method of the TextStream object. The Read method is used to read a specified number of characters in a file; the ReadLine method reads an entire line, but does not include a newline character; the ReadAll method reads the entire contents of the text file. The read content is stored in a string variable for display, parsing. When reading a file's contents using the Read or ReadLine method, skip or SkipLine method is used if you want to skip some parts.

The following code shows opening the file, filling in the data, and then reading the data:

Var fso, F1, TS, s; 

var ForReading = 1; 

FSO = new ActiveXObject ("Scripting.FileSystemObject"); 

Create file 

f1 = fso. CreateTextFile ("C:\\testfile.txt", true); 

Fill in one line of data 

F1. WriteLine ("Hello World"); 

F1. WriteBlankLines (1); 

Closes the file 

F1. Close (); 

Open file 

ts = fso. OpenTextFile ("C:\\testfile.txt", ForReading); 

Reads a file line to the string 

s = ts. ReadLine (); 

Display string Information 

alert ("File contents = '" + S + ""); 

Close File 

(v) Moving, copying and deleting documents

For the above three file operations, JavaScript has two corresponding methods: File.move or filesystemobject.movefile for moving files; file.copy Or filesystemobject.copyfile is used to copy files; File.delete or filesystemobject.deletefile is used to delete files.

The following code demonstrates creating a text file in the root directory of drive C, filling in some content, then moving the file to the \tmp directory, creating a copy of the file under the directory \temp, and finally deleting the files for both directories:

Var fso, F1, F2, s; 

FSO = new ActiveXObject ("Scripting.FileSystemObject"); 

F1 = fso. CreateTextFile ("C:\\testfile.txt", true); 

Write a line of 

F1. Write ("This is a test."); 

Closes the file 

F1. Close (); 

Gets the file handle F2 = FSO under the C:\ root directory 

. GetFile ("C:\\testfile.txt"); 

Move the file to the \tmp directory 

F2. Move ("C:\\tmp\\testfile.txt"); 

Copy the file to the \temp directory 

F2. Copy ("C:\\temp\\testfile.txt"); 

Gets the file handle 

F2 = fso. GetFile ("C:\\tmp\\testfile.txt"); 

F3 = FSO. GetFile ("C:\\temp\\testfile.txt"); 

Deletes the file 

F2. Delete (); 

Six, the conclusion

With the descriptions and examples of the various objects, properties, and methods of FileSystemObject, I believe you have a clear understanding of how to use the JavaScript language to manipulate drives, files, and folders on a page. However, the above mentioned routines are very simple, to fully and flexibly grasp the JavaScript file operation technology, but also need a lot of practical practice. There is also a reminder that because of advanced operations involving file reading and writing in a browser, there is an informational prompt before the code runs for the default browser security level.

The above is small make up for everyone to get the local file and directory of JS Method (recommended) All content, I hope we support cloud Habitat Community ~