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This article mainly introduces "jquery how to judge the existence of a tag". In daily operation, I believe many people have doubts about how to judge whether a tag exists in jquery. The editor consulted all kinds of data and sorted out a simple and easy-to-use method of operation. I hope it will be helpful to answer the doubt of "how to judge the existence of a tag by jquery". Next, please follow the editor to study!

Judgment method: 1, use the element selector to select the specified tag element, syntax "$(" tag signature ")", will return a jQuery object containing the specified element; 2, use the length attribute to determine whether the jQuery object is empty, syntax "object .length! = 0", if true is returned, it exists, and vice versa.

The operating environment of this tutorial: windows7 system, jquery1.10.2 version, Dell G3 computer.

Jquery's method to determine whether a tag exists or not

1. Use the jQuery element selector to select the specified element tag

The jQuery element selector selects elements based on the element name.

$("label signature")

For example, $("p") is selected.

Tag element.

A jQuery object containing the specified element is returned.

2. Use length attribute to judge whether the jQuery object is empty or not.

The length property gets the length of the jQuery object; you can then determine whether the object is empty by checking whether the length is 0.

JQuery object .length! = 0

If not empty (the return value is true), the specified label exists

If empty (return value is false), the specified label does not exist

Implementation example: determine whether p element and span element exist

.siblings, .siblings * {display: block; border: 2px solid lightgrey; color: lightgrey; padding: 5px; margin: 15px } # border {border: 2px solid pink } $(document) .ready (function () {$("button") .click (function () {var len1=$ ("p"). Length Var len2=$ ("span"). Length If (Len1Exp0) {console.log ("p element exists")} else {console.log ("p element does not exist") In ")} if (len2cm / 0) {console.log (" span element exists ")} else { Console.log ("span element does not exist")}}) }); div element

P (p element)

H3 (h3 element) h4 (h4 element)

P (p element)

Check whether p element and span element exist

As you can see, in the above example, the p element exists, while the span element does not exist.

At this point, the study on "how to determine whether a tag exists by jquery" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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