tsconfig: Enable composite.

This allows TypeScript to use incremental compilation by default.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

.gitignore

@@ -27,6 +27,7 @@
 
 ## Byproducts of setting up and using the dev environment
 *.pyc
+*.tsbuildinfo
 package-lock.json
 
 /.vagrant

tsconfig.json

@@ -28,6 +28,9 @@
 
         /* Language and Environment */
         "target": "ESNext",
+
+        /* Projects */
+        "composite": true,
     },
     "exclude": [
         // Type stubs are not part of the top-level project.

web/shared/package.json

@@ -3,7 +3,7 @@
   "version": "0.0.18",
   "license": "Apache-2.0",
   "scripts": {
-    "prepare": "rm -rf lib && tsc && cp src/*.flow lib",
+    "prepare": "tsc --build --clean && rm -rf lib && tsc && cp src/*.flow lib",
     "version": "tools/npm-version",
     "postversion": "tools/npm-postversion"
   },

web/shared/tsconfig.json

@@ -29,6 +29,9 @@
 
         /* Language and Environment */
         "target": "esnext",
+
+        /* Projects */
+        "composite": true,
     },
     "include": ["src"],
 }