What is the most effective method for retaining the state of a form that contains numerous sections?

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Using session storage or local storage in JavaScript would be the most effective method for retaining the state of a form that contains numerous sections. With session storage or local storage, the data entered in the form can be saved to the browser's cache, allowing the data to be retrieved even after the user closes the tab or entire browser window. Additionally, using a serialized format such as JSON to store the data makes it easier to retrieve and manipulate the form data when needed.