Promisify a callback-style function in just 4 lines of code
npm install promisify-4locConvert a Node.js-style callback API (err, val) => void to a Promise. Much like pify, but implemented in just 4 lines of code, with only the core functionality provided.
``
npm install --save promisify-4loc
Before:
`js
const fs = require('fs')
function main() {
fs.readFile('./test.js', (err, val) => {
if (err) console.error(err)
else console.log(val)
})
}
main()
`
After:
`js
const fs = require('fs')
const pify = require('promisify-4loc')
async function main() {
try {
const val = await pify(fs.readFile)('./test.js')
console.log(val)
} catch (err) {
console.error(err)
}
}
main()
`
It's called "4loc" because the implementation is only 4 lines of code:
`js``
module.exports = (fn) => (...args) =>
new Promise((resolve, reject) => {
fn(...args, (err, val) => err ? reject(err) : resolve(val))
})
That's 144 bytes.