Read and write binary types in files. This library allows you to use the functions you would use on a Buffer, like readUInt32, directly on files. It is promises-based.
npm install --save binary-file
Say you want to parse a simple binary file for an UInt32 containing the length of the string that follows. With binary-file, you can simply:
'use strict';
const BinaryFile = require('binary-file');
const myBinaryFile = new BinaryFile('./file.bin', 'r');
myBinaryFile.open().then(function () {
console.log('File opened');
return myBinaryFile.readUInt32();
}).then(function (stringLength) {
return myBinaryFile.readString(stringLength);
}).then(function (string) {
console.log(`File read: ${string}`);
return myBinaryFile.close();
}).then(function () {
console.log('File closed');
}).catch(function (err) {
console.log(`There was an error: ${err}`);
});And it looks even better with ES7 async / await:
'use strict';
const BinaryFile = require('binary-file');
const myBinaryFile = new BinaryFile('./file.bin', 'r');
(async function () {
try {
await myBinaryFile.open();
console.log('File opened');
const stringLength = await myBinaryFile.readUInt32();
const string = await myBinaryFile.readString(stringLength);
console.log(`File read: ${string}`);
await myBinaryFile.close();
console.log('File closed');
} catch (err) {
console.log(`There was an error: ${err}`);
}
})();You don't have to create a Buffer to write the data read from the file, you don't have to remember the position of the cursor: everything is handled by BinaryFile.
Create a new instance of BinaryFile.
path: the path of the file to openmode: the mode in which to open the file. See fs.openlittleEndian: endianness of the file
Open the file.
Return a promise.
fulfilled when the file is opened
Get the size in bytes of the file.
Return a promise.
fulfilled with the size of the file in bytes
Get the position of the cursor in the file.
Return the position of the cursor in the file.
Set the position of the cursor in the file
position: the position where to place the cursor
Return the new position.
Close the file.
Return a promise.
fulfilled when the file is closed
Read a Buffer in the file.
length: the number of bytes to readposition: the position where to read the Buffer in the file. If not set, it will use the internal cursor. If set, the internal cursor won't move
Return a promise.
fulfilled with the Buffer when the reading is done
Read a binary type in the file.
position: the position where to read the binary type in the file. If not set, it will use the internal cursor. If set, the internal cursor won't move
Return a promise.
fulfilled with the value read when the reading is done
Read a string in the file.
length: the number of bytes of the string to readposition: the position where to read the string in the file. If not set, it will use the internal cursor. If set, the internal cursor won't move
Return a promise.
fulfilled with the string read when the reading is done
Read a Buffer in the file.
buffer: the Buffer to writeposition: the position where to write the Buffer in the file. If not set, it will use the internal cursor. If set, the internal cursor won't move
Return a promise.
fulfilled with the number of bytes written when the writing is done
Write a binary type in the file.
value: the value to write in the corresponding binary typeposition: the position where to write the binary type in the file. If not set, it will use the internal cursor. If set, the internal cursor won't move
Return a promise.
fulfilled with the number of bytes written when the writing is done
Write a string in the file.
string: the string to writeposition: the position where to write the string in the file. If not set, it will use the internal cursor. If set, the internal cursor won't move
Return a promise.
fulfilled with the number of bytes written when the writing is done
- Prince Solomon princexz
All work contained in this project was completed as part of the curriculum for ALX Africa SE. ALX Africa is an online full-stack software engineering program that prepares students for careers in the tech industry using project-based peer learning. For more information, visit this link.
