jQuery Syntax

With jQuery you select (query) HTML elements and perform "actions" on them.

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jQuery Syntax Examples

$(this).hide()
Demonstrates the jQuery hide() method, hiding the current HTML element.

$("#test").hide()
Demonstrates the jQuery hide() method, hiding the element with id="test".

$("p").hide()
Demonstrates the jQuery hide() method, hiding all <p> elements.

$(".test").hide()
Demonstrates the jQuery hide() method, hiding all elements with class="test".

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jQuery Syntax

The jQuery syntax is tailor made for selecting HTML elements and perform some action on the element(s).

Basic syntax is: $(selector).action()

• A dollar sign to define jQuery
• A (selector) to "query (or find)" HTML elements
• A jQuery action() to be performed on the element(s)

Examples:

$(this).hide() - hides current element

$("p").hide() - hides all paragraphs

$("p.test").hide() - hides all paragraphs with class="test"

$("#test").hide() - hides the element with id="test"

	jQuery uses a combination of XPath and CSS selector syntax. You will learn more about the selector syntax in the next chapter of this tutorial.

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The Document Ready Function

You might have noticed that all jQuery methods, in our examples, are inside a document.ready() function:

$(document).ready(function(){

   // jQuery functions go here...

});

This is to prevent any jQuery code from running before the document is finished loading (is ready).

Here are some examples of actions that can fail if functions are run before the document is fully loaded:

• Trying to hide an element that doesn't exist
• Trying to get the size of an image that is not loaded