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JavaScript Treehouse Club: JavaScript Car Sounds Changing Keywords

Ryan Tung
PLUS
Ryan Tung
Courses Plus Student 2,216 Points

javescript:bikeBell();

What does the () mean? What is the usage? and why I have to put () at behind? is that necessary?

index.html
<!DOCTYPE html>
<html lang="en">

  <head>
  <meta name="charset" value="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=0.5, maximum-scale=0.5, minimal-ui">
    <title>Car Sounds</title>

    <!--Style Sheet link-->
    <link rel="stylesheet" type="text/css" href="css/style.css">
  </head>

  <body>

    <!--Car image -->
    <img src="images/bike.png" class="car" alt="car">


    <!--Button-->
    <a href="javascript:bikeBell();"><img src="images/bikeLock.png" alt="key"></a>


    <!--Audio Files-->
    <audio id="bikeBell" src="sounds/bikeBell.mp3" preload="auto"></audio>


    <!--Javascript-->
    <script type="text/javascript">
        function bikeBell() {
            document.getElementById('startCar').play();
        }

    </script>

  </body>

</html>

2 Answers

Billy Bellchambers
Billy Bellchambers
21,689 Points

All functions in JavaScript whether defined or not require the () this is used should you need to pass values into the function. and just part of the normal syntax.

By pass values to function see below.

function example(variable) {
  console.log(variable);
}

//when called the function will use the value passed to it inside the function

example(10);

//this will use the value of 10 wherever variable appears inside the function, this is only an example as always your variables can be called anything, have as many as you like by separating them with comma's or use none at all. Like in this example but the () still need to be there even if passing no values

example(10) {
  console.log(10);
}

//effect result like above

Hope this helps.

Happy coding!

Jennifer Nordell
seal-mask
STAFF
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

Those parentheses are an indication of a method or function. Actually a method is a function, it's just a function specifically attached to an object. Sometimes, as you probably know, a method/function will take arguments. If you don't have a parentheses it'll be looking for a variable. Ie xCount might be a variable that holds an int while xCount() might call a function that counts items in a list.