To understand the terms related to Node.js, I would like to discuss about Synchronization processing and Non Synchronization processing.
Synchronization processing and Non Synchronization processing
In Node.js the processes of file, network or input/output of database will be done by non synchronization processing to prioritize maximizing its performance.
Many libraries provides both non synchronization processing functions also synchronization processing functions as well.
| Non Synchronization processing | Synchronization processing | Meaning |
| fs.readFile() | fs.readFileSync() | Read file |
| fs.writeFile() | fs.writeFileSync() | Write file |
| fs.readdir() | fs.readdirSync() | Retrieve list of folders and files |
| zlib.gzip() | zlib.gzipSync() | Compress |
| crypto.pbkbf2() | crypto.pbkbf2Sync() | Encrypt password |
Actual example of Synchronization and Non Synchronization processing
const fs = require('fs')
//Load file in Synchronization -- A
const data = fs.readFileSync('test.txt', 'utf-8')
console.log(data)
//Load file in Non Synchronization --B
fs.readFile('test.txt', 'utf-8', readHandler)
// Once the loading has been done
function readHandler (err, data) {
console.log(data)
}The result
The results are the same with A and B. But Non Synchronization(B) needs additionally include the function that will be called after file loading.
C:\Users\Owner\Desktop\node>node sync-readfile.js This is the test. It is in "test.txt" // Result from A This is the test. It is in "test.txt" // Result from B
What is nameless function?
When we use nameless function we can easily define another new function. And the nameless function can be specified into function parameters as function objects.
// Example: transfer small caps to all caps
const s = 'Actions speak louder than words.'
const r = s.replace(/[a-z]+/g, function (m) {
returnm.toUpperCase()
})
console.log(r)
// Example: Sort numbers in an array
const ar = [100, 1, 30, 53, 20, 11, 4]
ar.sort((a, b) => {return b -a})
console.log(ar)The result
Like this example nameless function allows to define another function and the new function can be used as argument of functions or function objects.
C:\Users\Owner\Desktop\node>node mumei2.js ACTIONS SPEAK LOUDER THAN WORDS. [ 100, 53, 30, 20, 11, 4, 1 ]