This is the third installment of the 5 part set of Useful file operations in nodejs. Please check its part-1 and part-2 before proceeding any further. It is recommended but the contents are not inter-related so do as it suits your requirements.
It is used to open the file Asynchronously.The syntax of fs.open is fs.open(path, flags[, mode], callback) where [,mode] is optional. Their detailed explanation is as follows :
rs+ : It is used to open the file for reading and writing in Synchronous mode.It also instructs the OS to bypass the local file system cache . Moreover it is recommended not to use it unless you have no other choce because it affects the I/O performance. And It will not transforms fs.open() into a synchronous function. If that is what you want , you must use fs.openSync() which is explained later in this article.
w : It is used to open the file for writing. It will create the file if the file is non-existing and also if the file with the given name exists it will truncate it that it will delete all its content and provide us with a empty file.
wx : Just like w, It is also used to open the file for writing. It will also create the file if the file is non-existing but if the file already exists it will fail and throw an error.
// you have to pass the Relative path of the file from the Current working directory.
//The content to be appended is stored in variable "new_content" and it will be passed to the function.
new_content = "This data will be appended at the end of the file.";
fs.appendFile('data.txt', new_content , (err) => {
if(err)
throw err;
console.log('The new_content was appended successfully');
});
// To check it's Asynchronous nature !
console.log("This method is Asynchronous");