CSE 121B | JavaScript Callback Functions

Callback Functions

Overview

Callback functions are a powerful feature of JavaScript. They are used extensively in the JavaScript language and in the browser. Callback functions are used to handle events, to process data, and to control the flow of a program.

"A callback function is a function passed into another function as an argument, which is then invoked inside the outer function to complete some kind of routine or action." - MDN Web Docs

Prepare

Read 📝Callback Functions - MDN web docs
Ponder this article demonstrating the use of callback functions: Callback with built-in functions - devgenius.io

Check Your Understanding

Given these function declarations:

function calculate(a, b, callback) {
  callback(a + b);
}

function displayResult(result) {
  console.log('The result is: ' + result);
}

Call a function named calculate and pass it the arguments to support the console output of the following equation: 2 + 3.
💡Hint: You need to pass three arguments to the calculate function.
Answer
```
calculate(2, 3, displayResult)
```