Why Is Using `element.innerHTML =` Considered Bad Practice?

The Perils of Element.innerHTML =

Appending HTML content to an element using element.innerHTML = ... may seem like a convenient shortcut, but it can lead to performance issues and unexpected behavior.

Why it's Bad Code

When you assign a new value to element.innerHTML, the existing HTML is completely replaced. This triggers a browser re-parse of the entire subtree, which can be costly if the element contains a significant amount of complex HTML. The re-parsing can:

• Waste time and resources
• Break references to existing DOM elements
• Alter the layout and behavior of the page

Alternatives to innerHTML =

Instead, use appendChild() to append a new element to the end of an existing element. For instance:

var newElement = document.createElement('div');
newElement.innerHTML = '<div>Hello World!</div>';
element.appendChild(newElement);

This approach ensures that the existing HTML is preserved and no re-parsing occurs.

Optimization Note

Some browsers may have optimizations that prevent re-parsing when using innerHTML =. However, it's best to avoid this practice for consistency and performance reasons.

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