node. JS's fs Core module read-write file operation-----Easy-to-digest

node. js in FS module

Common features

Implementing read- Write directory operations for files

-Synchronous and asynchronous coexistence, asynchronous without synchronization

-Fs.readfile cannot read a file that is larger than the running memory and will not use the ReadFile method if the file is too large
-File large shunt read, stream

- introduction of FS module

-Let Fs=require (' FS ')

Read files synchronously

-fs.readfilesync(' path ', UTF8);

Let Result=fs.readfilesync ('./1.txt ', ' UTF8 ');

Asynchronously reads the file, catches the error with the parameter err

-FS. ReadFile (' path ', ' UTF8 ', function () {})

Fs.readfile ('./name.txt ', ' UTF8 ', function (err,data) {
if (err) {
Console.log (ERR)
}else{
Console.log (data)
}
})

Write files synchronously

- Fs.writefilesync("path", data written)

Fs.writefilesync ("./1.txt", Json.stringify ({name:1}))

Writing Files Asynchronously

- fs.writefile(' path ', data written, callback)

Fs.writefile ('./1.txt ', ' aaaaa ', function (err) {
if (err) {
Console.log (ERR);
}
})

Write a copy instance of a read-write file

Let Fs=require ("FS"); // Synchronous Copy function Copysync (source,target) {// synchronous Read let Result=fs.readfilesync (source, ' UTF8 '); // Synchronous Write Fs.writefilesync (Target,result);} Copysync ("./age.txt", './1.txt ');

Asynchronous copy

function Copy (sourse,target,callback) {
Asynchronous read
Fs.readfile (sourse, ' UTF8 ',function(err,data) {if(err) {return  Callback (ERR)}else{// asynchronously writes fs.writefile (Target,data,callback)}});}; Copy ('./name.txt ', './ss.txt ',function(err) {ifreturn  Console.log (err); Console.log (' copy succeeded ')})

determine if the file does not exist

- fs.existssync(' path to file ')

Stat method

Fs.stat (' File path ', function (Err,stat) {

Stat.isdirectory See if it's a folder
Stat.isfile See if it's a file

}）

Delete a folder

-Fs.rmdir (' folder path ', function () {})

deleting files

-Fs.unlink (' File path ', function () {})

Determine if the file does not exist

 if  (Fs.existssync ('./b '  './b ', function   (Err,stat) { Span style= "color: #008000;" >// stat is used for server caching  // stat.isdirectory look is not the folder Stat.isfile see is not the file  if   (Stat.isdirectory ()) { //  Delete folder  Fs.rmdir ('./b ', function   () {})}  else  {   delete file  fs.unlink ('./b ', function   () {});}})}  

Use recursion to write a folder and create it sequentially

functionMD (URL) {Let Paths=url.split ('/');//split the a/b/c into arrays [' A ', ' B ', ' C ']Let Index=0; functionMake (path) {if(index===paths.length+1) {//If you go to the end, stop recursion.            return false; }        if(!fs.existssync (path)) {//does not exist            //Create a folderFs.mkdir (Path,function() {Make (Paths.slice (0,++index). Join ('/'))            })        }Else{//existMake (Paths.slice (0,++index). Join ('/') }}} make (Paths[index++])//Take the first one out first.}MD (' A/B/C/D ');

node. JS's fs Core module read-write file operation-----Easy-to-digest