Understand SessionStorage and LocalStorage for Controlling Popups

When considering sessionStorage and localStorage for managing website popups, the main difference is in the duration of data storage and the way the popup is displayed.

1. sessionStorage

Data Life: Data persists only for the duration of the browser session. Once the tab or browser is closed, the data is cleared.

Use Case:

• Use sessionStorageif the popup should reappear each time the user opens the site in a new browser session.
• Example: You want to show a welcome popup only during a user's current session and not if they refresh the page or open the site in a different tab.

if (!sessionStorage.getItem('popupDisplayed')) {
    // Display popup
    alert('Welcome to the website!');
    sessionStorage.setItem('popupDisplayed', 'true');
}

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2. localStorage

Data Life: Data persists even after the browser is closed, until explicitly cleared by the user or via script.

Use Case:
Use localStorage if the popup should remain hidden across multiple sessions once a user has seen it.
Example: You want to display a promo popup only once a week or never again after the user dismisses it.

if (!localStorage.getItem('popupDisplayed')) {
    // Display popup
    alert('Check out our special offer!');
    localStorage.setItem('popupDisplayed', 'true');
}

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Key Differences for Popup Management:

Feature	sessionStorage	localStorage
Data Persistence	Only for the current session.	Persists indefinitely or until cleared.
Scope	Tab-specific.	Shared across all tabs/windows of the same origin.
When to Use	Temporary popups (e.g., session-only welcome message).	Persistent control (e.g., don't show again for a returning user).

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Decision Criteria:

• Short-term Popup Logic: Use sessionStorage if you want the popup to reappear in a new session.
• Persistent Popup Logic: Use localStorage if the popup logic needs to persist even after the browser or tab is closed.

For more complicated situations, you may even use custom logic to mix both storages (e.g., session-based for a week).