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Add Class

This lesson is part of How To · All levels

Summary

Add class is used to add one or more CSS classes to an element via JavaScript. The method maintains an existing class and ignores the class that has been added. This approach is safer than overriding the entire class attribute with a classname.

Key points

ClassList.add('name') adds a class without removing another class
Several classes can be added at once as separate arguments
Adding the same class twice doesn't cause duplication.
Avoid 'new' because you delete an existing class

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