Dummy Proof: Callback Functions

What is a callback function?

• A function passed as an argument inside of a function that will be executed later

When to use a callback ?

• You can use callbacks in asynchronous functions, where one function has to wait for another function to invoke.

Regular Function :

function name(argument){
   //do something 
}

Callback Function :

//Defining functions
function prepare(ingredients, callback) {
       console.log("Preparing " + ingredients);
       callback();
}

//callback function
function chop(){
       console.log("Chopping");
}

//Calling the function
prepare("onions and garlic", chop);

function createQuote(quote, callback){ 
  var myQuote = "Like I always say, " + quote;
  callback(myQuote); // 2
}

function logQuote(quote){
  console.log(quote);
}

createQuote("eat your vegetables!", logQuote); // 1

// Result in console: 
// Like I always say, eat your vegetables!

Things to know about callback functions :

• It's a function that is passed as an argument to another function
• Does not have to be named 'callback' in the argument
• This function is called a higher-order function which contains the logic for when the callback function gets executed
• JavaScript has anonymous functions which lets you declare and execute functions without naming them.
• Callback functions can be anonymous functions

Resources:

• https://www.freecodecamp.org/news/javascript-callback-functions-what-are-callbacks-in-js-and-how-to-use-them/#:~:text=As%20we%20can%20see%2C%20the,task%20as%20the%20example%20above.
• https://developer.mozilla.org/en-US/docs/Glossary/Callback_function#:~:text=A%20callback%20function%20is%20a,kind%20of%20routine%20or%20action.&text=The%20above%20example%20is%20a,as%20it%20is%20executed%20immediately.
• https://www.w3schools.com/js/js_callback.asp