Reading JSON from localStorage
type Result =
| { success: true, value: unknown }
| { success: false, error: Error };
function tryDeserializeLocalStorageItem(key: string): Result {
const item = localStorage.getItem(key);
if (item === null) {
// The item does not exist, thus return an error result
return {
success: false,
error: new Error(`Item with key "${key}" does not exist`)
};
}
let value: unknown;
try {
value = JSON.parse(item);
} catch (error) {
// The item is not valid JSON, thus return an error result
return {
success: false,
error
};
}
// Everything's fine, thus return a success result
return {
success: true,
value
};
}