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TypeScript Blueprints by Ivo Gabe de Wolff

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Adding persistent storage

When the user closes and reopens the app, the user sees an empty list of scans. We can make the list persistent by saving it after a scan and loading it when the app starts. We can use the application-settings module to store the scans. The storage is based on key-value: a value is assigned to a specific key.

Only booleans, numbers, and strings can be stored using this module. An array cannot be stored. Instead, one could store the length under one key (for instance, items-length) and the items under a set of keys (items-0, items-1, ...). An easier approach is to convert the array to a string using JSON.

The list can be saved using the following function:

function save() { applicationSettings.setString("items", JSON.stringify(items)); ...

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