Storage Data Migration

Storage Migration

When your data schema changes between app versions, use a version key to detect and migrate old formats on startup.

Example

const STORAGE_VERSION = 2;

function migrateStorage() {
  const version = parseInt(localStorage.getItem("version") || "1");

  if (version < 2) {
    // v1 stored name, v2 stores { firstName, lastName }
    const name = localStorage.getItem("name");
    if (name) {
      const [firstName, ...last] = name.split(" ");
      localStorage.setItem("user", JSON.stringify({ firstName, lastName: last.join(" ") }));
      localStorage.removeItem("name");
    }
  }

  localStorage.setItem("version", String(STORAGE_VERSION));
}

migrateStorage(); // Run on app start

JAVASCRIPT

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Pro Tip

Version your localStorage schema and always run migration code before reading data on app startup.

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