How Can I Reliably Determine if an Image Has Loaded Successfully Using jQuery?

Determining Image Load Status with jQuery: A Comprehensive Solution

When using jQuery to handle image manipulations, it's essential to know whether an image has successfully loaded or if an error has occurred. To address this, jQuery offers the load() and error() events. However, a common pitfall arises when an error occurs before jQuery can register these events.

To tackle this issue, it's recommended to check the complete property of the image DOM element after assigning the load() and error() events. This ensures that the image wasn't loaded prematurely, even before jQuery's event registration.

However, if an error occurs prior to jQuery's event registration, the complete property remains unreliable. In such cases, a more robust approach is necessary.

Solution: Inspecting Multiple Properties

The recommended solution involves examining both the complete and naturalWidth properties of the image in sequence:

1. Check the complete property. If it's false, it indicates that the image may not have loaded or an error occurred.
2. If complete is false, verify the naturalWidth property. For broken images, this property will typically be 0.

By combining these checks, you can accurately determine whether an image has loaded or if an error has been encountered, even in situations where jQuery's event registration is hindered.

Here's an example code snippet:

function IsImageOk(img) {
    // Check if the image is already loaded
    if (!img.complete) {
        return false;
    }

    // If not loaded, check the naturalWidth property to determine if an error occurred
    if (img.naturalWidth === 0) {
        return false;
    }

    // No errors detected, assume the image is loaded successfully
    return true;
}

By implementing this solution, you can effectively handle image loading in your jQuery-based applications, ensuring that appropriate actions are taken based on the image's status.

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