`window.onload vs document.onload: Which Event Handler Has Better Browser Compatibility?`

window.onload vs document.onload: Understanding Browser Compatibility

Question: Which event handler between window.onload and document.onload offers broader browser support?

Answer:

Event Firing Behavior

window.onload:

• Traditionally, window.onload fires upon the complete loading of the entire webpage, including all external content (images, stylesheets, scripts).
• In recent browsers, it has also assumed the role of document.onload, firing when the Document Object Model (DOM) has initialized.

document.onload:

• This event triggers specifically when the DOM is ready, which may occur before the loading of other content like images.

Browser Compatibility

• window.onload: This event handler enjoys wider support across browsers. In fact, some modern browsers have essentially replaced document.onload with window.onload.

• document.onload: It is less widely supported than window.onload. Due to compatibility concerns, many developers have turned to JavaScript libraries like jQuery to handle document readiness checks:

  $(document).ready(function() { /* code here */ }); // using jQuery
  $(function() { /* code here */ }); // alias for $(document).ready()

Historical Comparison: window.onload vs body.onload

Similar to the window.onload vs document.onload question, there was a discussion about using window.onload instead of body.onload. The consensus was to prefer window.onload, as it helps separate structure from event handling.

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