Hello morning to you all, welcome to my new tutorial on JavaScript. In my last tutorial post we rounded up all about JavaScript function.
In this tutorial we are going to be discussing Events in JavaScript. JavaScript's interaction with HTML is handled through events that do occur whenever the user or the browser manipulates a page.
In this tutorial we are going to be discussing Events in JavaScript. JavaScript's interaction with HTML is handled through events that do occur whenever the user or the browser manipulates a page.
When the page loads, it is called an event. When the user clicks a button, that click too is an event. Other examples include events like pressing a key, closing a window, resizing a window, etc.
Developers can make use of these events to execute the JavaScript coded responses, which in return cause buttons to close windows, messages to be displayed to the users, information to be validated, and virtually any other type of responses imaginable.
Developers can make use of these events to execute the JavaScript coded responses, which in return cause buttons to close windows, messages to be displayed to the users, information to be validated, and virtually any other type of responses imaginable.
Events are a part of the Document Object Model (DOM) Level 3 and every Html element contains a set of events which can be used to trigger Javascript code. Let's take a look at few examples below in order to learn and understand the relationship between the Event and JavaScript.
You can also read our tutorial post on: Learn how to implement JavaScript Literals with examples
onclick Event Type
This is the most often used event type which occurs when the user clicks on the left button of his/her mouse. You can put your warning, validation, etc., against this event type.
Example
Try the following example below for better understanding.
<html>
<head>
<script type = "text/javascript">
<!--
function sayHello() {
alert("Hello World");
}
//-->
</script>
</head>
<body>
<p>Click the following button to see result</p>
<form>
<input type = "button" onclick = "sayHello()" value = "Click" />
</form>
</body>
</html>
<head>
<script type = "text/javascript">
<!--
function sayHello() {
alert("Hello World");
}
//-->
</script>
</head>
<body>
<p>Click the following button to see result</p>
<form>
<input type = "button" onclick = "sayHello()" value = "Click" />
</form>
</body>
</html>
Output
Below is the output of the above example.
Click the following button to see result
You can also read our tutorial post on: Steps on how to implement JavaScript Nested functions with examples
Onsubmit Event Type
Onsubmit is an event that occurs when you try to submit a form. You can put in your form validation against this event type.
Example
The following example shows how to use onsubmit. Here we are calling a validate() function before submitting a form data to the web server. If validate() method returns true, the form will be submitted, otherwise it will not submit the data.
Try the following example below for better understanding.
Try the following example below for better understanding.
<html>
<head>
<script type = "text/javascript">
<!--
function validation() {
all validation goes here
..........................................
returns either true or false
}
//-->
</script>
</head>
<body>
<form method = "POST" action = "t.cgi" onsubmit = "return validate()">
...........................................
<input type = "submit" value = "Submit" />
</form>
</body>
</html>
<head>
<script type = "text/javascript">
<!--
function validation() {
all validation goes here
..........................................
returns either true or false
}
//-->
</script>
</head>
<body>
<form method = "POST" action = "t.cgi" onsubmit = "return validate()">
...........................................
<input type = "submit" value = "Submit" />
</form>
</body>
</html>
You can also read our tutorial post on: JavaScript - while Loop
onmouseover and onmouseout
These two event types is going to help you create nice effects with images or even with text as well. The onmouseover event triggers when you bring your mouse over any element and the onmouseout event triggers when you move your mouse out from that element.
Try the following example below for better understanding.
Try the following example below for better understanding.
<html>
<head>
<script type = "text/javascript">
<!--
function over() {
document.write("Mouse Over");
}
function out() {
document.write("Mouse Out");
}
//-->
</script>
</head>
<body>
<p>Bring your mouse inside the division to see result:</p>
<div onmouseover = "over()" onmouseout = "out()">
<h1>This is inside the division</h1>
</div>
</body>
</html>
<head>
<script type = "text/javascript">
<!--
function over() {
document.write("Mouse Over");
}
function out() {
document.write("Mouse Out");
}
//-->
</script>
</head>
<body>
<p>Bring your mouse inside the division to see result:</p>
<div onmouseover = "over()" onmouseout = "out()">
<h1>This is inside the division</h1>
</div>
</body>
</html>
Output
Below is the output of the above example
Bring your mouse inside the division to see result
This is inside the division
HTML 5 Standard Events
The HTML 5 standard events are listed below for your reference. Here script indicates a JavaScript function to be executed against that event.
| Attribute | Value | Description |
|---|---|---|
| Offline | script | Triggers when the document goes offline |
| Onabort | script | Triggers on an abort event |
| onafterprint | script | Triggers after the document is printed |
| onbeforeonload | script | Triggers before the document loads |
| onbeforeprint | script | Triggers before the document is printed |
| onblur | script | Triggers when the window loses focus |
| oncanplay | script | Triggers when media can start play, but might has to stop for buffering |
| oncanplaythrough | script | Triggers when media can be played to the end, without stopping for buffering |
| onchange | script | Triggers when an element changes |
| onclick | script | Triggers on a mouse click |
| oncontextmenu | script | Triggers when a context menu is triggered |
| ondblclick | script | Triggers on a mouse double-click |
| ondrag | script | Triggers when an element is dragged |
| ondragend | script | Triggers at the end of a drag operation |
| ondragenter | script | Triggers when an element has been dragged to a valid drop target |
| ondragleave | script | Triggers when an element is being dragged over a valid drop target |
| ondragover | script | Triggers at the start of a drag operation |
| ondragstart | script | Triggers at the start of a drag operation |
| ondrop | script | Triggers when dragged element is being dropped |
| ondurationchange | script | Triggers when the length of the media is changed |
| onemptied | script | Triggers when a media resource element suddenly becomes empty. |
| onended | script | Triggers when media has reach the end |
| onerror | script | Triggers when an error occur |
| onfocus | script | Triggers when the window gets focus |
| onformchange | script | Triggers when a form changes |
| onforminput | script | Triggers when a form gets user input |
| onhaschange | script | Triggers when the document has change |
| oninput | script | Triggers when an element gets user input |
| oninvalid | script | Triggers when an element is invalid |
| onkeydown | script | Triggers when a key is pressed |
| onkeypress | script | Triggers when a key is pressed and released |
| onkeyup | script | Triggers when a key is released |
| onload | script | Triggers when the document loads |
| onloadeddata | script | Triggers when media data is loaded |
| onloadedmetadata | script | Triggers when the duration and other media data of a media element is loaded |
| onloadstart | script | Triggers when the browser starts to load the media data |
| onmessage | script | Triggers when the message is triggered |
| onmousedown | script | Triggers when a mouse button is pressed |
| onmousemove | script | Triggers when the mouse pointer moves |
| onmouseout | script | Triggers when the mouse pointer moves out of an element |
| onmouseover | script | Triggers when the mouse pointer moves over an element |
| onmouseup | script | Triggers when a mouse button is released |
| onmousewheel | script | Triggers when the mouse wheel is being rotated |
| onoffline | script | Triggers when the document goes offline |
| onoine | script | Triggers when the document comes online |
| ononline | script | Triggers when the document comes online |
| onpagehide | script | Triggers when the window is hidden |
| onpageshow | script | Triggers when the window becomes visible |
| onpause | script | Triggers when media data is paused |
| onplay | script | Triggers when media data is going to start playing |
| onplaying | script | Triggers when media data has start playing |
| onpopstate | script | Triggers when the window's history changes |
| onprogress | script | Triggers when the browser is fetching the media data |
| onratechange | script | Triggers when the media data's playing rate has changed |
| onreadystatechange | script | Triggers when the ready-state changes |
| onredo | script | Triggers when the document performs a redo |
| onresize | script | Triggers when the window is resized |
| onscroll | script | Triggers when an element's scrollbar is being scrolled |
| onseeked | script | Triggers when a media element's seeking attribute is no longer true, and the seeking has ended |
| onseeking | script | Triggers when a media element's seeking attribute is true, and the seeking has begun |
| onselect | script | Triggers when an element is selected |
| onstalled | script | Triggers when there is an error in fetching media data |
| onstorage | script | Triggers when a document loads |
| onsubmit | script | Triggers when a form is submitted |
| onsuspend | script | Triggers when the browser has been fetching media data, but stopped before the entire media file was fetched |
| ontimeupdate | script | Triggers when media changes its playing position |
| onundo | script | Triggers when a document performs an undo |
| onunload | script | Triggers when the user leaves the document |
| onvolumechange | script | Triggers when media changes the volume, also when volume is set to "mute" |
| onwaiting | script | Triggers when media has stopped playing, but is expected to resume |
Alright guys! This is where we are rounding up for this tutorial post. In my next tutorial, we are going to be studying about Javascript and cookies.
Feel free to ask your questions where necessary and i will attend to them as soon as possible. If this tutorial was helpful to you, you can use the share button to share this tutorial.
Follow us on our various social media platforms to stay updated with our latest tutorials. You can also subscribe to our newsletter in order to get our tutorials delivered directly to your emails.
Thanks for reading and bye for now.
Feel free to ask your questions where necessary and i will attend to them as soon as possible. If this tutorial was helpful to you, you can use the share button to share this tutorial.
Follow us on our various social media platforms to stay updated with our latest tutorials. You can also subscribe to our newsletter in order to get our tutorials delivered directly to your emails.
Thanks for reading and bye for now.