snapshot of https://github.com/tldraw/tldraw.git (main, 2026-09-23; blobs > 131072B omitted)

packages/worker-shared/src/env.ts

@@ -0,0 +1,49 @@
+import { getOwnProperty } from '@tldraw/utils'
+
+/**
+ * Validates that specified environment variables are present and non-nullish in the provided environment object.
+ * Throws an error if any required variables are missing, otherwise returns the environment with guaranteed
+ * non-nullable types for the specified keys.
+ *
+ * @param env - The environment object containing potential environment variables
+ * @param keys - An object specifying which keys from the environment are required, where each key maps to `true`
+ * @returns The environment object with type-safe guarantees that the specified keys are non-null and defined
+ * @throws Error When any of the specified required environment variables are undefined
+ *
+ * @example
+ * ```typescript
+ * interface MyEnv {
+ *   readonly DATABASE_URL?: string
+ *   readonly API_KEY?: string
+ *   readonly OPTIONAL_VAR?: string
+ * }
+ *
+ * const env: MyEnv = {
+ *   DATABASE_URL: 'postgres://...',
+ *   API_KEY: 'secret-key',
+ *   // OPTIONAL_VAR is undefined
+ * }
+ *
+ * // Validate only the required variables
+ * const config = requiredEnv(env, {
+ *   DATABASE_URL: true,
+ *   API_KEY: true,
+ * })
+ *
+ * // config.DATABASE_URL and config.API_KEY are now guaranteed to be strings
+ * console.log(config.DATABASE_URL) // TypeScript knows this is string, not string | undefined
+ * ```
+ *
+ * @public
+ */
+export function requiredEnv<T extends object>(
+	env: T,
+	keys: { [K in keyof T]: true }
+): { [K in keyof T]-?: NonNullable<T[K]> } {
+	for (const key of Object.keys(keys)) {
+		if (getOwnProperty(env, key) === undefined) {
+			throw new Error(`Missing required env var: ${key}`)
+		}
+	}
+	return env as any
+}