JavaScript Timers

Question 1

What is a “callback” function?

Answer 1

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.

Question 2

Besides adding an event listener callback function to an element or the document, what is one way to delay the execution of a JavaScript function until some point in the future?

Answer 2

To delay a function call, use setTimeout() function

Question 3

How can you set up a function to be called repeatedly without using a loop?

Answer 3

setInterval(function, milliseconds ) Same as setTimeout(), but repeats the execution of the function continuously.

Question 4

What is the default time delay if you omit the delay parameter from setTimeout() or setInterval()?

Answer 4

If you omit it, the delay defaults to 0.

Question 5

What do setTimeout() and setInterval() return?

Answer 5

setInterval() a numeric, non-zero value

The setTimeout() returns a timeoutID which is a positive integer identifying the timer created as a result of calling the method.

timeoutID is the positive integer

setTimeout allows us to run a function once after the interval of time. setInterval allows us to run a function repeatedly, starting after the interval of time, then repeating continuously at that interval