This time I will bring you a detailed explanation of the use of jQuery's three $()s. What are the precautions for the use of jQuery's three $()s. The following is a practical case, let's take a look.
$ is an alias for jQuery "class", and $() constructs a jQuery object. Therefore, "$()" can be called jQuery's constructor (personal opinion, haha!).
1. $() can be $(expresion), that is, css selector , Xpath or html element, that is, the target element is matched through the above expression.
For example: The object constructed by $("a") uses a CSS selector to construct a jQuery object - it selects all the tags. For example:
$("a").click(function(){...})
is the trigger event when any link on the page is clicked. To be precise, jQuery constructs an object $("a") using the tag , and the function click() is an (event) method of this jQuery object.
For example, there is such a piece of HTML code:
<p>one</p> <p> <p>two</p> </p> <p>three</p> <a href="#" id="test" onClick="jq()" >jQuery</a>
The operation of this HTML is the following statement:
alert($("p>p").html());
$() is a query expression, that is, using " A query expression such as p>p" constructs a jQuery object, and then "html()" means to display its html content, which is the [two] of the above HTML code snippet. Another example:
$("<p><p>Hello</p></p>").appendTo("body");
$() contains a string. Use such a string to construct a jQuery object, and then add this string to
$(document).find("p>p").html());
$() is a DOM element, that is, it searches for the
element with
in the full text, and displays the content in
.
3. $() can be $(function), that is, a function, which is a shorthand for $(document).ready(). For example, the common form is like this:
$(document).ready(function(){ alert("Hello world!"); });
Deformable operation:
$(function(){ alert("Hello world!"); });
对于选择HTML文档中的elements,jQuery有两种方法:
1)如$("p>ul a"),它的意思是p标签中的ul标签中的a标签
不过,$('p>ul')和$('p ul')是有区别的,
$('p>ul')是
的直接后代里找
的所有后代里找
的直接后代里找
的所有后代里找
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