Accessing object property values using dot notation and brackets- clarification on when brackets must be used?

Question

For this class a for-loop was created inside the callback function to process an XML HTTP request. This callback functions runs through the following data string, converted it to a JavaScript array of objects, and then creates a bit of HTML stating whether each employee is in or out of the office.

[
  {
   "name": "Aimee",
   "inoffice": false
  },
  {
   "name": "Amit",
   "inoffice": false
  },
  {
   "name": "Andrew",
   "inoffice": true
  },
  {
   "name": "Ben",
   "inoffice": true
  },

//etc etc

I set up my for looping using a template literal like so:

const xhr = new XMLHttpRequest();

xhr.onreadystatechange = function () {
  if(xhr.readyState === 4) {
    let employees = JSON.parse(xhr.responseText);
    let statusHTML = `<ul class="bulleted">`;
    for (let i = 0; i < employees.length; i++) {
     if (employees[i]['inoffice'] === false) {
       statusHTML += `<li class="out">${employees[i]['name']}</li>`;
     } else {
       statusHTML += `<li class="in">${employees[i]['name']}</li>`;
     }
    }
    statusHTML += `</ul>`;
    document.getElementById('employeeList').innerHTML = statusHTML;
  }
};

xhr.open('GET', 'data/employees.json');

xhr.send();

Unlike Dave, I used bracket notation to access the property values of each property within each object. I did this because of the earlier JS Objects course, which explained that running through the values of an object, you should use bracket notation over dot notation whilst in a 'for-in' loop, like this:

for (let property in person) {
    console.log(`${property}: ${[property]}`);
}
//returns:
// name: Edward
// nickname: Duke
// etc etc
//i.e. values are dynamically filled in

//NOTE: we CAN'T do this:
for (let property in person) {  
    console.log(`${property}: ${person.prop}`);
}
//As the console then outputs undefined for each value:
//Returns:
// name: undefined
// nickname: undefined
// etc etc

I think I got a bit confused by this. Am I right in thinking that using brackets only (not dot notation) applies only to this case when we are using a for-in loop on an object, and not in other cases such as the one presented in the class?

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James Croxford

James Croxford

Accessing object property values using dot notation and brackets- clarification on when brackets must be used?