function mainFunc(){
    for(let i=1;i<=5;i++){
      let final = "";
      for(let j=1;j<=5;j++){
        if(i === 1 || i === 5 || j === 1 || j === )
        {
           final += "*"
        } else {
           final += " "
        }
    }
    console.log(final);
  }
}
mainFunc

output 
*****
*   *
*   *
*   *
*****

for (let i = 0; i < 4; i++) {
    let row = '';
    for (let j = 0; j < 4; j++) {
      row += '*';
    }
    console.log(row);
  }

output
****
****
****
****