Explain Callback functions in Javascript?

JavaScript functions are executed in the sequence they are called. Not in the sequence they are defined. A callback is a function passed as an argument to another function. The print( ) function takes another function as a parameter and calls it inside. This is valid in JavaScript and we call it a “callback”. So a function that is passed to another function as a parameter is a callback function.

Using a callback, you could call the calculator function (my calculator) with a callback, and let the calculator function run the callback after the calculation is finished:

When to Use a Callback?

  { name: "Barronette Peak" },
  { $set: { name: "Baronette Peak" } },
  function(error, result) {
    if (!error) {
      console.log(`Operation completed successfully: ${result.ok}`);
    } else {
      console.log(`An error occurred: ${error}`);

Where callbacks really shine is in asynchronous functions, where one function has to wait for another function (like waiting for a file to load).