Node.js fs.write() Method
The fs.write() method is an inbuilt application programming interface of fs module which is used to specify the position in a file to begin writing at a buffer to write, as well as which part of the buffer to write out to the file. The fs.write() method can also be used without a buffer by simply using a string variable. The examples given below demonstrate the use of buffer as well as string in the fs.write() method. It is an asynchronous method.
- Using buffer
fs.write(fd, buffer, offset, length, position, callback)
- Using string
fs.write(fd, string, position, encoding, callback)
Parameters: The method accept the following parameters as mentioned above and described below:
- fd: A file descriptor the value returned by opening the file using the fs.open() method. It contains an integer value.
- buffer: It contains the buffer type value like Buffer, TypedArray, DataView.
- offset: It is an integer value that determines the part of the buffer to be written to the file.
- length: It is an integer value that specifies the number of bytes to write into the file.
- position: It is an integer value that holds the position refers to the offset from the beginning of the file where the data is to be written.
- callback: It contains callback function that receives error and number of bytes written to the file.
- string: Write string to the file specified by fd.
- encoding: The default encoding value is UTF-8.
Return Value: The callback function receives either error or the number of bytes written. If an error is received then an error message is printed else the number of bytes written is printed.
51 characters added to file
input.txt file data:
GeeksforGeeks: A computer science portal for geeks
On successful execution of the program, the data stored in the buffer is appended to the required file. In case the file does not exist beforehand, a new file is created and data is appended to it.
11 bytes written
input.txt file data:
Explanation: On successful execution of the program, the string value is written(appended) to the required file.