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JavaScript Callback Functions in JavaScript Introduction to Callback Functions Using a Function as a Callback

Posted by Dionte Barnes
Dionte Barnes
10,140 Points

There is some code in the app.js file that needs to be completed. functionRunner has one argument missing, the callback.

I need a little help with this please!

app.js 
function log() {
  console.log("Hello World!");
}

functionRunner();
index.html 
<!DOCTYPE html>
<html lang="en">
    <head>
        <title></title>
        <link rel='stylesheet' href='styles.css'>
    </head>
    <body>
        <section>
            <p>Open your browser's console to see the results</p>
        </section>
        <script src='runner.js'></script>
        <script src='app.js'></script>
    </body>
</html>
runner.js 
function functionRunner(callback) { 
  callback();
}

1 Answer

scribbles
scribbles
21,173 Points
scribbles
scribbles
21,173 Points

If you look at the 'functionRunner' function it takes one parameter called 'callback' that is what is meant by one argument is missing. You just need to pass an argument to serve as the callback parameter, in this case it will be the log method that is declared in the app.js file.

function log() {
  console.log("Hello World!");
}

functionRunner(log);

Passing 'log' to the 'functionRunner' function as an argument/parameter will pass the 'log' function to functionRunner to be run as the callback.

Dionte Barnes
Dionte Barnes
10,140 Points

Dude, literally after sent the message I looked at the code and I realized that the "log" was what I was missing! Thanx!