Is it okay to use a "for in" loop inside of the "for" loop to print out each of the key/value pairs?

The benefit is also the downside.

As you point out, looping through the properties will show any new ones that have been added. But it will not show any expected ones that are missing. In the original solution, a missing property would still be named and listed as "undefined", but in the modified strategy, it would simply not be shown. The data might also be occasionally contain private fields only intended for authorized viewers that would be exposed by the new method.

So each method would be best suited to different requirements. Do you want to list only certain fields and alert the viewer to missing data, or do you want to just list the entire database contents?

Hi David, As with almost everything in development, there are always multiple roads that will lead to the same result. In this particular example, it is certainly possible to (and in my opinion a better practice to) use automation in the way of iterating with loops and built-in JS methods.

A couple things if you'll allow me: in your code you are making a global variable of the student by not using a var, let, or const keyword. The keyword let is a great new ES6 feature the allows developers to use block scope variables, meaning their values will never leak out of the (block/function/for-loop) scope they were created in. As you continue on your journey learning JavaScript, you'll learn more eloquent ways to perform the same tasks, as you already have by keeping your code DRY in your example above!

Here's an example of code progression that I hope inspires you to learn more as I was learning to code only a year and half ago: THIS

let message = '';
function createDataSheet(studentData, output) {
  for(let i=0, l=studentData.length; i<l; i++) {
    message += '<h2>Student: ' + studentData[i].name +'</h2>';
    for(let key in studentData[i]) {
      message += '<p>' + [key] + ': ' + studentData[i][key] +'</p>';
    }
  }
}
createDataSheet(students, message)

console.log(message);

IS THE SAME AS THIS

let message = '';
function createDataSheet(studentData, output) {
  for(let i=0, l=studentData.length; i<l; i++) {
    message += `<h2>Student: ${studentData[i].name}</h2>`;
    for(let key in studentData[i]) {
      message += `<p>${key}: ${studentData[i][key]}</p>`;
    }
  }
}
createDataSheet(students, message)

console.log(message);

IS THE SAME AS THIS

const createDataSheet = (data, input) => {
  data.forEach((student) => {
    input += `<h2>Student: ${student.name}</h2>`;
    Object.keys(student).forEach(key => input += `<p>${key}: ${student[key]}</p>` );
  });
  return input;
};
console.log(createDataSheet(students, ''));

The difference in from the last version to the first is that in the last version I am using built-in methods. As you learn more and begin using built-in methods you'll find that using these methods over traditional for-loops and for-in loops will lower the chance of creating an unknown/unseen error.

Hope this helps and happy coding :) Rich