使用 .append() 後如何用 jQuery 檢查元素是否存在？

Verifying Element Existence in jQuery

When attempting to ascertain the presence of an element using the .append() method, the default syntax of $('elemId').length may prove ineffective. This issue arises from the omission of the hash (#) before the element identifier.

Solution:

To successfully check the existence of an element created via the .append() method, the proper syntax requires the inclusion of a hash (#) before the element's ID. Here's the corrected code:

$('#elemId').length

Rationale:

In JavaScript, accessing elements by ID typically involves using the document.getElementById() method without the hash. However, when using jQuery, the hash (#) is essential for targeting elements based on their ID, analogous to the behavior in CSS.

Therefore, to verify the existence of an element created using the .append() method, the corrected syntax $('#elemId').length must be employed, ensuring that the hash precedes the element's ID.

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