JavaScript イベント ハンドラーが追加された要素でトリガーに失敗するのはなぜですか?

Why JavaScript Event Handlers Aren't Triggering for Appended Elements

When you append new elements to the DOM, such as in the provided HTML code, JavaScript event handlers that were previously defined may not recognize the new elements. This can lead to unexpected behavior, as the JavaScript code relies on the presence of specific elements to trigger events.

To resolve this issue, you need to use event delegation. Event delegation is a technique where you attach an event handler to a parent element that exists at the time the page loads. When an event occurs on a child element that was appended later, the event will bubble up to the parent element, and the event handler attached to the parent will be triggered.

In the provided code, you have attached click event handlers to the .races elements. However, when new elements are added to the DOM, jQuery does not recognize them because they were not present when jQuery initialized on page load.

To fix this, you can delegate the click event to the nearest parent element that exists at page load, such as the .races container div. Here's the updated code:

$(document).ready(function(){
  $('.races-container').on('click', '.races', function(e){
    ... // Your event handler code
  })
});

By delegating the event to the .races-container div, jQuery will be able to handle clicks on both existing and newly appended .races elements, ensuring that your event handler is triggered correctly.

Remember that event delegation is a common technique when working with dynamically generated content, as it allows you to handle events on elements that may not exist at the time of page load.

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