What to do if the javascript selector fails

The JavaScript selector fails because the code is not standardized. The solution is: 1. Remove the imported JS code and the ID selector method will be effective; 2. Introduce it before introducing "jquery.js" Just specify the JS code.

The operating environment of this tutorial: Windows 10 system, javascript version 1.8.5, Dell G3 computer.

What should I do if the javascript selector fails?

jQuery’s ID selector failure problem

jQuery’s ID selector works fine in other files in the same project;

On the current page, other jQuery functions (such as: $(document).ready(function(){ alert("ok"); });) run normally,

but the ID selector method fails, such as alert($("#user")) results in null.

Cause:

The current page has introduced some JS codes, which may be caused by irregularities in these codes.

Solution:

(1) Remove the imported JS code, the ID selector method is valid;

(2) Because these JS codes must be used, so after the introduction These JS codes were introduced before jquery.js, and the ID selector method was tested to be effective.

Related extensions:

#The id selector selects elements with the specified id.

id refers to the id attribute of the HTML element.

Note: The id attribute must be unique within the document.

Note: Do not use id attributes starting with numbers! This may cause problems in some browsers.

Syntax

$("#id")参数：

id Required. Specifies the id of the element to be selected.

Recommended study: "JavaScript Video Tutorial"

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