Why is incorrect (outdated) data coming to the server?

Question

JavaScript

There is a request handler from the server, the task of which is to call the function I wrote, which in turn will overwrite the json file, which should be further sent to the server.

Server part

router.post('/currentDir1', (req, res) =>{  
        console.log("POST");
        const fs = require('fs');
        let body = "";   
        let pathToFile = "";
        console.log(req.body);        
        
        req.on("data", function (data) {
            body += data;
        });
        
        req.on("end", function(currentData) {
            console.log(JSON.parse(body));
            currentData = JSON.parse(body);


        console.log("еще тут");

        async function takeValue(){
                if(currentData.sizeOrType === "<папка>"){
                    let dir = currentData.dir + currentData.fileName;
                    // dir = "C:\\totalcmd";
                    console.log(dir);                
                    if(currentData.whichScreen){
                        console.log(currentData.whichScreen);                    
                        let result = await foo(dir, './data/firstScreen.json');
                        pathToFile = './data/firstScreen.json';
                    
                        var json1 = JSON.parse(fs.readFileSync('./data/firstScreen.json', 'utf8'));
                          
                        if(result){
                            console.log("таку хули"); 
                            console.log(json1);                 
                            res.json(json1);
                        }                        
                    
                    }else{
                        console.log('aaaa');
                        foo(dir, './data/secondScreen.json');
                        pathToFile = './data/firstScreen.json';
                        res.sendFile(path.resolve('./data/secondScreen.json'));
                        
                    } 
                    
                }
                   
            }
            console.log("я тут");
            takeValue();          
        });      
    })

The main function that is responsible for rewriting json

const fs = require('fs');

var Foo = async function(dir, pathToFile){
    let Mode = require('stat-mode'); // проверка дириктори или файл
    let temp; //вспомогательная переменная 
    let jsonFile = { 
        table: []
     };

     console.log("FOO WAS STARTED");
    
     fs.readdir(dir, function(err, items) {   // Вроде работает :)
        for (let i=0; i<items.length; i++) { //массив всех файлов текущей директории       
            try{                  
                fs.stat(dir +"\\"+ items[i], function(err, stats){
                        // console.log(dir +"\\"+ items[i]);
                        try{
                            let mode = new Mode(stats); // определяем папка или файл             
                            if(mode.isDirectory()){
                            temp = "<папка>";
                            } else{
                                temp = stats.size.toString() + " байт";
                            }                
                            jsonFile.table.push({icon:i, fileName:items[i], sizeOrType: temp , dateOfChange: stats.mtime, dir: dir}); //добавляем данные                    
                             fs.writeFile(pathToFile, JSON.stringify(jsonFile), (err)=>{
                                if(err) console.log("error");
                            });
                            
                        }
                        catch(e){
                            console.log(e);
                        }
                });
            }
            catch(e){                
                console.log(e);
                continue;
            }        
        }    
    });
    return true;
}

Just in case, I will attach a piece that sends a request to the server, but I do not think that the problem is in it.

methods:{
        clickOnRow: function(elem, whichScreen){
          this.clicks++   
          if(this.clicks === 1) {
            var self = this
            this.timer = setTimeout(function() {            
            console.log("одинарный");                 
              self.clicks = 0
            }, this.delay);
          } else{
             clearTimeout(this.timer);
             console.log("двойной");

             console.log(elem);
             
             elem['whichScreen']  = whichScreen;    
            //  console.log(this.helper);
            //  this.nameOfMethod(elem);
             this.clicks = 0; 
            fetch('/currentDir1',{
                    method: 'POST',
                    mode: 'cors',
                    headers: {
                        'Content-Type': 'application/json',
                        'Accept': 'application/json'                 
                    },
                    body: JSON.stringify(elem)                
                    })
                    // .then(response => console.log(response))  
                    .then(response => response.json())    
                    .then(json => this.helper = json.table)
                    .then(json => console.log(json))
                    
                    .then(this.$emit("newvalue", this.helper, whichScreen))

Answer 1

Did you think you wrote a word asyncand it suddenly became asynchronous by itself? Nothing like this. You have everything scattered into a bunch of parallel executable functions, and no one is waiting for anyone. Learn async in javascript or use synchronous functions (with postfix Sync).