The bellow generates a file containing code and prints the output of the program:

 class Code {
  static list = require("./settings.json");
  static fs = require("fs");
  constructor(
    code="print('Hello World')",//default code
    lang = "py",//language
    fn = "test",//file name
    args = "" //arguments
  ) {
    this.code = code;
    const path = require('path');
    this.fn = path.join(__dirname,fn) + "." + lang;//for platform independence
    this.run_com = Code.replace(Code.list[lang], this.fn, args);
    this._output="Server not responding";
              this._error="Server not responding";
  }

  file_exists()
  {
    return Code.fs.existsSync(`${this.fn}`);
  }

  make_file() {
    Code.fs.writeFile(`${this.fn}`, this.code, (err) => {
      if (err) {
        console.log(err);
      }
    });
  }

  run_file()
  {
      if(!this.file_exists())
      this.make_file();

      const { exec } = require("child_process");
      
      exec(this.run_com, (error, stdout, stderr) =>{
          if(error)
          {
              console.log(error);
          }
          
          else if(stderr==""){
          this._output=stdout;
          this._error="No error";
      }

          else{
          this._error=stderr;
          this._output=stdout;
          }
          console.log(this);//this
        });
        console.log(this);//this
  }

  get error()
  {
      return this._error;
  }

  get output()
  {
      return this._output;
  }

  static replace(
    s //replace {}
  ) {
    const arg = Object.values(arguments).slice(1); //convert obj to array removing s
    for (let i in arg) {
      s = s.replace("{}", arg[i]);
    }
    return s;
  }
}

a = new Code("print('exd')");
a.run_file();

In the above program the output is:

The change in the state of object is not persistent once it comes out of the inner function.

why does the second console.log prints first and why the output of both the console.log are different, please justify in detail.

Also suggest a solution of this problem.