Introduction
In this lesson we will look at functions as arguments - passing functions into functions.
This is something that happens frequently. Functions get passed into other functions and are executed inside the receiving function.
We will first take a look at how that works, and then discuss practical implementations of this pattern when looking at:
- forEach method
- setTimeout method
- setInterval method
Functions as arguments
These are often called callbacks. It is very common to pass functions as arguments to other functions and have the receiving function execute them.
forEach method
The forEach method (function) is an alternative to the for loop.
When you use a forEach function, you will pass in a function to be executed by the forEach function for each item in the array you are looping over.
It does have some limitations though, such as the inability to use break or continue.
setTimeout
The setTimeout method is used to execute a function after a specified period.
It has the following structure:
setTimeout(function () {
// do something},
1000);
It has two required arguments:
- the function to be executed.
- the delay - the delay in milliseconds before the function is executed.
SetInterval
The setInterval method is similar to setTimeout but it executes a function at a certain interval until it is cleared.
It has the following structure:
setInterval(function () {
// do something
}, 1000);
Lesson Task
Brief
There are practice questions in the master branch of this repo.
Attempt the answers before checking them against the answers in the answers branch of the repo.