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How To Detect If Domcontentloaded Was Fired

When coding, it's crucial to know when the DOMContentLoaded event is fired. This event signals that the HTML document has been fully loaded and parsed, allowing your JavaScript code to safely interact with the document. In this article, we'll walk you through how to detect if DOMContentLoaded was fired in your web application.

One way to detect the firing of this event is by using the document.readyState property. When the DOMContentLoaded event is fired, the value of document.readyState changes to 'interactive'. You can check the value of this property using a simple JavaScript conditional statement:

Js

if(document.readyState === 'interactive') {
  // DOMContentLoaded event has been fired
  console.log('DOMContentLoaded event fired');
}

Another method is to directly listen for the DOMContentLoaded event using the addEventListener method. Here's how you can do it:

Js

document.addEventListener('DOMContentLoaded', function() {
  // DOMContentLoaded event handler
  console.log('DOMContentLoaded event fired');
});

By using this approach, you set up an event listener that triggers the specified function when the DOMContentLoaded event occurs, providing you with a clear indication that the event has been fired.

In some cases, you may need to detect whether the DOMContentLoaded event has already fired before adding an event listener. You can achieve this by checking if the document.readyState property is already set to 'interactive'. If it is, you can directly execute your code; otherwise, you can add an event listener for future firing:

Js

if(document.readyState === 'interactive') {
  // DOMContentLoaded has already fired
  console.log('DOMContentLoaded has already fired');
} else {
  // Add an event listener for future firing
  document.addEventListener('DOMContentLoaded', function() {
    console.log('DOMContentLoaded event fired');
  });
}

This approach ensures that your code is executed correctly, whether the DOMContentLoaded event has already been fired or not.

Additionally, you can also use libraries like jQuery to handle the DOMContentLoaded event. In jQuery, you can achieve this using the `$(document).ready()` method:

Js

$(document).ready(function() {
  // DOMContentLoaded event handler using jQuery
  console.log('DOMContentLoaded event fired');
});

By utilizing these methods, you can effectively detect if DOMContentLoaded was fired in your web application, ensuring that your JavaScript code runs at the right time and interacts seamlessly with the fully loaded HTML document. Remember, understanding when this event occurs is crucial for building responsive and well-performing web applications.

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