sfcode
An Online Competing and Development Environment
About fs.read() & fs.write()

fs.read() & fs.write() are different from other fs methods in that their callbacks are called with 3 arguments instead of the usual 2 arguments.

If you're using them with callbacks, they will behave as usual. However, their promise usage is a little different. fs-extra promisifies these methods like util.promisify() (only availible in Node 8+) does.

Here's the example promise usage:

<tt>fs.read()</tt>

// Basic promises
fs.read(fd, buffer, offset, length, position)
.then(results => {
console.log(results)
// { bytesRead: 20, buffer: <Buffer 0f 34 5d ...> }
})
// Async/await usage:
async function example () {
const { bytesRead, buffer } = await fs.read(fd, Buffer.alloc(length), offset, length, position)
}

<tt>fs.write()</tt>

// Basic promises
fs.write(fd, buffer, offset, length, position)
.then(results => {
console.log(results)
// { bytesWritten: 20, buffer: <Buffer 0f 34 5d ...> }
})
// Async/await usage:
async function example () {
const { bytesWritten, buffer } = await fs.write(fd, Buffer.alloc(length), offset, length, position)
}