Read and write file operations based on FS core module (example explanation)

fs module

Commonly used functions

Implementing the fileRead and write directory operations

- Synchronous and asynchronous coexistence, no synchronous if there is asynchronous

- No files with larger memory than running, and if the file is too large, you won't use the readFile method

- Large file diversion reading, stream

- Introducing the fs module

- let fs=require('fs')

Read files synchronously

-('Path',utf8);

let result=('./','utf8');

Read files asynchronously, use parameter err to catch errors

- ('Path','utf8',function(){})

('./','utf8',function(err,data){
if(err){
(err)
}else{
(data)
}
})

Synchronously write files

- ("Path", data written)

("./",({name:1}))

Asynchronously write files

- ('Path', data written, callback)

('./','aaaaa',function (err) {
if(err){
(err);
}
})

Read and write a copy instance of the file

let fs=require("fs");
//Synchronous copyfunction copySync(source,target){
//Synchronous readinglet result=(source,'utf8');
//Synchronous write(target,result);
}
copySync("./",'./');

//Asynchronous copy

function copy(sourse,target,callback){
//Asynchronous reading(sourse,'utf8',function(err,data){
if(err){
return callback(err)
}else{
//Asynchronous write(target,data,callback)
}
});
};
copy('./','./',function(err){
if(err) return (err);
('Copy successfully')
})

Determine whether the file exists or not

- ('Path to file')

stat method

('File Path',function (err,stat) {

See if it is a folder
See if it is a file

}）

Delete folder

- ('Folder Path',function(){})

Delete files

- ('File Path',function(){})

//Judge whether the file exists or not

if(('./b')){
('./b',function (err,stat) {
//The time in stat is used for server cache//See if it is a folder? See if it is a file?if(()){
//Delete the folder('./b',function(){})
}else{
//Delete the file('./b',function(){});
}
})
}

Use recursion to write a folder to create it in sequence

function md(url) {
  let paths=('/'); //Split a/b/c into an array ['a','b','c']  let index=0;
  function make(path){
    if(index===+1){ // If you reach the end point, stop recursion      return false;
    }
    if(!(path)){ //Not exists      //Create a folder      (path,function () {
        make((0,++index).join('/'))
      })
    }else{ //exist      make((0,++index).join('/'))
    }
  }
  make(paths[index++]) //Take out the first one first}
md('a/b/c/d');

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