Functions are segments of your script that do not run until they are called to execute in your document. They can be executed by HTML events or Javascript events, and they will only run when that event fires off. The various examples below lend good insight into the aspects of function creation.
Any user initiated event can make your function run
Javascript CODE EXAMPLE
<script type="text/javascript">
function myFunction(){
var status = document.getElementById("status");
status.innerHTML = "You just made my function run.";
}
</script>
<p><input type="button" value="Click Me" onclick="myFunction()"></p>
<h3 id="status"></h3>
An event of the window or document can make your function run
Javascript CODE EXAMPLE
<script type="text/javascript">
function myFunction(){
var status = document.getElementById("status");
status.innerHTML = "The page finishing loading made my function run.";
}
window.onload = myFunction;
</script>
<h3 id="status"></h3>
Make your functions more powerful by adding arguments
Arguments are an aspect of function creation that make your functions much more dynamic, useful and reusable. You can apply one or more arguments to your functions, if applying multiple arguments be sure to separate each by a comma.
Javascript CODE EXAMPLE
<script type="text/javascript">
function myFunction(v1,v2,v3){
var status = document.getElementById("status");
status.innerHTML = v2+" has known "+v1+" for "+v3+" years.";
}
</script>
<p><input type="button" value="Click Me" onclick="myFunction('Joe','Ben',7)"></p>
<h3 id="status"></h3>
Javascript does not require an event necessarily in order to run a function
Javascript CODE EXAMPLE
function myFunction(){
alert("Function called to run by Javascript");
}
myFunction(); // calls the function run
