feat: allow import.meta.hot define override

packages/vite/src/node/__tests__/plugins/define.spec.ts

@@ -37,4 +37,19 @@ describe('definePlugin', () => {
       'const isSSR = false;'
     )
   })
+
+  test('preserve import.meta.hot with override', async () => {
+    // assert that the default behavior is to replace import.meta.hot with false
+    const transform = await createDefinePluginTransform()
+    expect(await transform('const isHot = import.meta.hot;')).toBe(
+      'const isHot = false;'
+    )
+    // assert that we can specify a user define to preserve import.meta.hot
+    const overrideTransform = await createDefinePluginTransform({
+      'import.meta.hot': 'import.meta.hot'
+    })
+    expect(await overrideTransform('const isHot = import.meta.hot;')).toBe(
+      'const isHot = import.meta.hot;'
+    )
+  })
 })

packages/vite/src/node/plugins/define.ts

@@ -45,13 +45,15 @@ export function definePlugin(config: ResolvedConfig): Plugin {
       ...config.env,
       SSR: !!config.build.ssr
     }
+    // put import.meta.hot replacement in importMetaKeys to allow
+    // users to override with config.define.
+    importMetaKeys['import.meta.hot'] = `false`
     for (const key in env) {
       importMetaKeys[`import.meta.env.${key}`] = JSON.stringify(env[key])
     }
     Object.assign(importMetaFallbackKeys, {
       'import.meta.env.': `({}).`,
-      'import.meta.env': JSON.stringify(config.env),
-      'import.meta.hot': `false`
+      'import.meta.env': JSON.stringify(config.env)
     })
   }