Table of Contents
Brief Overview:
In the previous posts I explained how javascript will be used to create the programs for the dynamic web application . I used the word dynamic , because it makes the web page interactive.
In this section , I want to discuss two important features known as ,DOM and Event Handling. These features make the javascript differ from regular programming language.
DOM:
DOM full form is Document Object Modelling
The JavaScript DOM defines a standard for accessing documents in the web page:
“The W3C Document Object Model (DOM) is a platform and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of a document.”
There are 3 types of DOM :
- Core DOM – standard model for all document types
- XML DOM – standard model for XML documents
- HTML DOM – standard model for HTML documents
Each type is given by the following diagrams :
XML DOM
DOM
The above diagrams illustrates the DOM of above three types.
Event Handling is another powerful feature of Javascript ,which enables the web page dynamic for programming the html elements .
What is Event Handling?
For example consider a mouse click , this is an HTML event , The javascript will react to these events. It is called handling the event . For ex: onclock() is an event is used on clicking a button , we need to define the function ,when the click on the button done. It is called handling the event .This is employed by Javascript DOM
The different events supported by Javascript is as follows:
The events are classified into Input events ,Mouse Events ,click events and Other events.
the different events supported in Javascript is as follows:
Event and it’s Description Table
| Event | Description | Belongs To |
|---|---|---|
| abort | The event occurs when the loading of a media is aborted | UiEvent, Event |
| afterprint | The event occurs when a page has started printing, or if the print dialogue box has been closed | Event |
| animationend | The event occurs when a CSS animation has completed | AnimationEvent |
| animationiteration | The event occurs when a CSS animation is repeated | AnimationEvent |
| animationstart | The event occurs when a CSS animation has started | AnimationEvent |
| beforeprint | The event occurs when a page is about to be printed | Event |
| beforeunload | The event occurs before the document is about to be unloaded | UiEvent, Event |
| blur | The event occurs when an element loses focus | FocusEvent |
| canplay | The event occurs when the browser can start playing the media (when it has buffered enough to begin) | Event |
| canplaythrough | The event occurs when the browser can play through the media without stopping for buffering | Event |
| change | The event occurs when the content of a form element, the selection, or the checked state have changed (for <input>, <select>, and <textarea>) | Event |
| click | The event occurs when the user clicks on an element | MouseEvent |
| contextmenu | The event occurs when the user right-clicks on an element to open a context menu | MouseEvent |
| copy | The event occurs when the user copies the content of an element | ClipboardEvent |
| cut | The event occurs when the user cuts the content of an element | ClipboardEvent |
| dblclick | The event occurs when the user double-clicks on an element | MouseEvent |
| drag | The event occurs when an element is being dragged | DragEvent |
| dragend | The event occurs when the user has finished dragging an element | DragEvent |
| dragenter | The event occurs when the dragged element enters the drop target | DragEvent |
| dragleave | The event occurs when the dragged element leaves the drop target | DragEvent |
| dragover | The event occurs when the dragged element is over the drop target | DragEvent |
| dragstart | The event occurs when the user starts to drag an element | DragEvent |
| drop | The event occurs when the dragged element is dropped on the drop target | DragEvent |
| durationchange | The event occurs when the duration of the media is changed | Event |
| ended | The event occurs when the media has reach the end (useful for messages like “thanks for listening”) | Event |
| error | The event occurs when an error occurs while loading an external file | ProgressEvent, UiEvent, Event |
| focus | The event occurs when an element gets focus | FocusEvent |
| focusin | The event occurs when an element is about to get focus | FocusEvent |
| focusout | The event occurs when an element is about to lose focus | FocusEvent |
| fullscreenchange | The event occurs when an element is displayed in fullscreen mode | Event |
| fullscreenerror | The event occurs when an element can not be displayed in fullscreen mode | Event |
| hashchange | The event occurs when there has been changes to the anchor part of a URL | HashChangeEvent |
| input | The event occurs when an element gets user input | InputEvent, Event |
| invalid | The event occurs when an element is invalid | Event |
| keydown | The event occurs when the user is pressing a key | KeyboardEvent |
| keypress | The event occurs when the user presses a key | KeyboardEvent |
| keyup | The event occurs when the user releases a key | KeyboardEvent |
| load | The event occurs when an object has loaded | UiEvent, Event |
| loadeddata | The event occurs when media data is loaded | Event |
| loadedmetadata | The event occurs when meta data (like dimensions and duration) are loaded | Event |
| loadstart | The event occurs when the browser starts looking for the specified media | ProgressEvent |
| message | The event occurs when a message is received through the event source | Event |
| mousedown | The event occurs when the user presses a mouse button over an element | MouseEvent |
| mouseenter | The event occurs when the pointer is moved onto an element | MouseEvent |
| mouseleave | The event occurs when the pointer is moved out of an element | MouseEvent |
| mousemove | The event occurs when the pointer is moving while it is over an element | MouseEvent |
| mouseover | The event occurs when the pointer is moved onto an element, or onto one of its children | MouseEvent |
| mouseout | The event occurs when a user moves the mouse pointer out of an element, or out of one of its children | MouseEvent |
| mouseup | The event occurs when a user releases a mouse button over an element | MouseEvent |
| mousewheel | Deprecated. Use the wheel event instead | WheelEvent |
| offline | The event occurs when the browser starts to work offline | Event |
| online | The event occurs when the browser starts to work online | Event |
| open | The event occurs when a connection with the event source is opened | Event |
| pagehide | The event occurs when the user navigates away from a webpage | PageTransitionEvent |
| pageshow | The event occurs when the user navigates to a webpage | PageTransitionEvent |
| paste | The event occurs when the user pastes some content in an element | ClipboardEvent |
| pause | The event occurs when the media is paused either by the user or programmatically | Event |
| play | The event occurs when the media has been started or is no longer paused | Event |
| playing | The event occurs when the media is playing after having been paused or stopped for buffering | Event |
| popstate | The event occurs when the window’s history changes | PopStateEvent |
| progress | The event occurs when the browser is in the process of getting the media data (downloading the media) | Event |
| ratechange | The event occurs when the playing speed of the media is changed | Event |
| resize | The event occurs when the document view is resized | UiEvent, Event |
| reset | The event occurs when a form is reset | Event |
| scroll | The event occurs when an element’s scrollbar is being scrolled | UiEvent, Event |
| search | The event occurs when the user writes something in a search field (for <input=”search”>) | Event |
| seeked | The event occurs when the user is finished moving/skipping to a new position in the media | Event |
| seeking | The event occurs when the user starts moving/skipping to a new position in the media | Event |
| select | The event occurs after the user selects some text (for <input> and <textarea>) | UiEvent, Event |
| show | The event occurs when a <menu> element is shown as a context menu | Event |
| stalled | The event occurs when the browser is trying to get media data, but data is not available | Event |
| storage | The event occurs when a Web Storage area is updated | StorageEvent |
| submit | The event occurs when a form is submitted | Event |
| suspend | The event occurs when the browser is intentionally not getting media data | Event |
| timeupdate | The event occurs when the playing position has changed (like when the user fast forwards to a different point in the media) | Event |
| toggle | The event occurs when the user opens or closes the <details> element | Event |
| touchcancel | The event occurs when the touch is interrupted | TouchEvent |
| touchend | The event occurs when a finger is removed from a touch screen | TouchEvent |
| touchmove | The event occurs when a finger is dragged across the screen | TouchEvent |
| touchstart | The event occurs when a finger is placed on a touch screen | TouchEvent |
| transitionend | The event occurs when a CSS transition has completed | TransitionEvent |
| unload | The event occurs once a page has unloaded (for <body>) | UiEvent, Event |
| volumechange | The event occurs when the volume of the media has changed (includes setting the volume to “mute”) | Event |
| waiting | The event occurs when the media has paused but is expected to resume (like when the media pauses to buffer more data) | Event |
| wheel | The event occurs when the mouse wheel rolls up or down over an element | WheelEvent |
I conclude here for this post , if you have any queries please comment below , I will come up another post with event handling mechanism with code.