Created
August 28, 2018 01:46
-
-
Save billautomata/58a8d4b8bc6b102f65841db80ad2c28f to your computer and use it in GitHub Desktop.
dealing with callbacks
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| // nest them | |
| var a = 0 | |
| var b = 0 | |
| fs.readFile('filename.txt', function(err,data){ | |
| a = data | |
| fs.readFile('file2.txt', function(err,data){ | |
| b = data | |
| console.log(a,b) // both values | |
| }) | |
| }) | |
| // use a library called async | |
| // npm install --save async | |
| var async = require('async') | |
| var fns = [] // array of functions | |
| var a = 0 | |
| var b = 0 | |
| // push a function on to the array | |
| fns.push(function(done){ | |
| fs.readFile('filename.txt', function(err,data){ | |
| a = data | |
| return done() // a special async function that signals to move on | |
| }) | |
| }) | |
| // push another function on to the array | |
| fns.push(function(done){ | |
| fs.readFile('file2.txt', function(err,data){ | |
| b = data | |
| return done() // a special async function that signals to move on | |
| }) | |
| }) | |
| // push the last function on to the array | |
| fns.push(function(done){ | |
| console.log(a,b) // both values are populated | |
| return done() | |
| }) | |
| async.series(fns) // this is where all the 3 functions you just pushed on to the array are run in order | |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment