feat(core): expose isServer value to reuse across app (#258)

.changeset/great-eyes-divide.md

@@ -0,0 +1,5 @@
+---
+"@t3-oss/env-core": minor
+---
+
+expose isServer value to reuse across app

examples/astro/src/t3-env.ts

@@ -15,3 +15,5 @@ export const env = createEnv({
   skipValidation: import.meta.env.SKIP_ENV_VALIDATION === "development",
   clientPrefix: "PUBLIC_",
 });
+
+const isServer = env.isServer;

examples/nextjs/app/env.ts

@@ -18,3 +18,5 @@ export const env = createEnv({
   },
   extends: [vercel()],
 });
+
+const isServer = env.isServer;

examples/nuxt/env.ts

@@ -9,3 +9,5 @@ export const env = createEnv({
     NUXT_PUBLIC_GREETING: z.string(),
   },
 });
+
+const isServer = env.isServer;

packages/core/src/index.ts

@@ -209,7 +209,7 @@ export type CreateEnv<
       TypeOf<ZodObject<TClient>> &
       TypeOf<ZodObject<TShared>> &
       UnReadonlyObject<Reduce<TExtends>>
-  >
+  > & { isServer: boolean }
 >;
 
 export function createEnv<
@@ -294,6 +294,7 @@ export function createEnv<
       if (typeof prop !== "string") return undefined;
       if (ignoreProp(prop)) return undefined;
       if (!isValidServerAccess(prop)) return onInvalidAccess(prop);
+      if (prop === "isServer") return isServer;
       return Reflect.get(target, prop);
     },
     // Maybe reconsider this in the future:

packages/core/test/smoke.test.ts

@@ -620,3 +620,25 @@ describe("extending presets", () => {
     });
   });
 });
+
+describe("isServer is correctly exposed", () => {
+  test("for server", () => {
+    const env = createEnv({
+      server: {},
+      runtimeEnv: {},
+      isServer: true,
+    });
+
+    expect(env.isServer).toBe(true);
+  });
+
+  test("for client", () => {
+    const env = createEnv({
+      server: {},
+      runtimeEnv: {},
+      isServer: false,
+    });
+
+    expect(env.isServer).toBe(false);
+  });
+});