jQuery provides the is() method to easily determine whether an element is visible, hidden, and selected.
1. Determine whether the element is hidden
The div element in the following html is hidden:
2. Determine whether the checkbox is selected
In jquery, you can use xx.is(':checked') to determine whether checkbox and radiobutton are selected. Test html as follows
3. Determine whether a certain style is used
is function introduction< /title><br> <style> //Set some basic styles<br> div { width:60px; height:60px; margin:5px; float:left;<br> border:4px outset; background:green; text -align:center;<br> font-weight:bolder; cursor:pointer; }<br> .blue { background:blue; } //Style 1<br> .red { background:red; }//Style 2<br> span { color:white; font-size:16px; }<br> p { color:red; font-weight:bolder; background:yellow;<br> margin:3px; clear:left; display:none; } <br> </style><br> <script src="http://code.jquery.com/jquery-1.9.1.js"></script> //Note that jQuery is used here Official script library<br></head><br><body><br> <div></div> //Note that the first div appears here<br><div class=" blue"></div>//Note that the second div appears here<br><div></div>//Note that the third div appears here<br><div class=" red"></div>//Note that the fourth div appears here
<p><div><br/><span>Peter</span></div>//Note that the fifth div appears here<br><div class="blue"> </div>//Note that the 6th div appears here<br><p> </p><br><script><br> $("div").one('click', function () { //$("div").one represents attaching an event to the div element, <br>//You can also attach multiple events, such as click or mouseout to execute something at the same time <br> if ($(this ).is(":first-child")) { //is function comes into play, is(":first-child") represents <br> //Judge whether this div is the first div to appear<br> $ ("p").text("It's the first div."); //The difference between text and html is whether it supports html tags <br> // If you write an alert in it at this time, it will not be executed <br> } else if ($(this).is(".blue,.red")) { //Determine whether the div has a blue or red class<br> $("p").text("This is blue or red Red div");<br> } else if ($(this).is(":contains('Peter')")) { //Determine whether the word Peter exists in the div<br> $("p" ).text("It's Peter!");<br> } else {<br> } $("p").html("It's nothing <em>special</em>.");<br> }<br> $("p").hide().slideDown("slow"); //This is an animation effect that slowly displays the content of p<br> $(this).css({"border-style" : "inset", cursor:"default"});<br> });<br></script></p>
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