Modifying HTML Content and Attributes

const span = document.createElement('span');
span.dataset.userId = '123';
span.setAttribute('data-user-id', '123');

Always use setAttribute
Always use dataset
The dataset property is the modern and recommended way to work with data attributes. It provides a cleaner, more intuitive API where data attributes are automatically mapped to camelCase properties (data-user-id becomes dataset.userId). While setAttribute works, dataset is more maintainable and less prone to errors as it handles the data- prefix automatically and provides type checking in TypeScript.
Use dataset for simple values, setAttribute for complex ones
They are interchangeable, use either