Why Does jQuery Only Select the First Element with a Duplicate ID?

Invalid HTML: Multiple Elements with the Same ID

Problem Description:

In the given HTML structure, there are three buttons with the same ID, "xyz." However, when using the jQuery ID selector $("#xyz") to handle onClick events, only the first button responds. The other buttons are ignored.

Analysis:

The jQuery ID selector is designed to select the first element with a matching ID in the document. However, according to W3C specifications, an ID value should be unique within the document. Having multiple elements with the same ID is considered invalid HTML.

As mentioned in the jQuery API documentation, if more than one element has the same ID, the jQuery selector will only select the first matching element. Relying on this behavior is not recommended, and the HTML should be corrected to ensure uniqueness of IDs.

Solution:

To resolve this issue, replace the id attribute with a class attribute for the buttons. This will allow the buttons to have different values without violating the HTML validation rules.

Revised HTML:

<button type="button" class="btn btn-primary xyz" value="1">XYZ1</button>
<button type="button" class="btn btn-primary xyz" value="2">XYZ2</button>
<button type="button" class="btn btn-primary xyz" value="3">XYZ3</button>

Updated jQuery Script:

To handle the click events for all buttons with the xyz class, use the following jQuery code:

$(".xyz").click(function(){
    // Get the value of the button that was clicked
    var xyz = this.value;

    // Display the value in an alert box
    alert(xyz);
});

This updated code will properly handle the onClick events for all three buttons and display their respective values in alert boxes.

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