Fix fallback to source builds

Continue to run build-on-demand.mjs to permit a fallback to a
from-source build for users who run `npm install slint-ui` on a platform
where we don't provide binaries for (such as linux-armv7/64). However,
this is only done when run from the installed package, not from git.
From git, the prestart trick remains in use.

api/node/build-on-demand.mjs

@@ -6,6 +6,7 @@
 
 import { Worker } from "node:worker_threads";
 import { spawn } from "node:child_process";
+import { existsSync } from "node:fs";
 
 const worker = new Worker("./rust-module.cjs");
 // Define dummy error handler to prevent node from aborting on errors
@@ -14,9 +15,19 @@ worker.on("error", (error) => {
 });
 worker.on("exit", (code) => {
     if (code !== 0) {
-        console.log("slint-ui: loading rust-module.cjs failed, building now");
-        spawn("npm", ["run", "build"], {
-            stdio: "inherit",
-        });
+        // HACK: npm package removes .npmignore. If the file is present, then it means that we're in the Slint git repo,
+        // and we don't want to automatically build (see https://github.com/slint-ui/slint/pull/6780).
+        if (existsSync("./.npmignore")) {
+            console.log(
+                "slint-ui: loading rust-module.cjs failed, please run `npm run build` first.",
+            );
+        } else {
+            console.log(
+                "slint-ui: loading rust-module.cjs failed, building now",
+            );
+            spawn("npm", ["run", "build"], {
+                stdio: "inherit",
+            });
+        }
     }
 });

api/node/package.json

@@ -40,6 +40,7 @@
     "build": "napi build --platform --release --js rust-module.cjs --dts rust-module.d.ts -c binaries.json",
     "build:debug": "napi build --platform --js rust-module.cjs --dts rust-module.d.ts -c binaries.json && pnpm compile",
     "build:testing": "napi build --platform --js rust-module.cjs --dts rust-module.d.ts -c binaries.json --features testing && pnpm compile",
+    "install": "node build-on-demand.mjs",
     "docs": "pnpm build && typedoc --hideGenerator --treatWarningsAsErrors --readme cover.md typescript/index.ts",
     "check": "biome check",
     "format": "biome format",

demos/home-automation/node/package.json

@@ -9,7 +9,7 @@
     },
     "scripts": {
         "start": "node .",
-        "prestart": "cd ../../../api/node/ && node build-on-demand.mjs && pnpm compile",
+        "prestart": "cd ../../../api/node/ && pnpm run build && pnpm compile",
         "check": "biome check",
         "format": "biome format",
         "format:fix": "biome format --write",

demos/printerdemo/node/package.json

@@ -8,6 +8,6 @@
     },
     "scripts": {
         "start": "node .",
-        "prestart": "cd ../../../api/node/ && node build-on-demand.mjs && pnpm compile"
+        "prestart": "cd ../../../api/node/ && pnpm run build && pnpm compile"
     }
-}
+}

examples/carousel/node/package.json

@@ -8,6 +8,6 @@
     },
     "scripts": {
         "start": "node .",
-        "prestart": "cd ../../../api/node/ && node build-on-demand.mjs && pnpm compile"
+        "prestart": "cd ../../../api/node/ && pnpm run build && pnpm compile"
     }
-}
+}

examples/imagefilter/node/package.json

@@ -13,7 +13,7 @@
     },
     "scripts": {
         "start": "tsc --build && node ./main.js",
-        "prestart": "cd ../../../api/node/ && node build-on-demand.mjs && pnpm compile",
+        "prestart": "cd ../../../api/node/ && pnpm run build && pnpm compile",
         "type-check": "tsc --noEmit"
     }
 }

examples/memory/package.json

@@ -8,6 +8,6 @@
     },
     "scripts": {
         "start": "node .",
-        "prestart": "cd ../../api/node/ && node build-on-demand.mjs && pnpm compile"
+        "prestart": "cd ../../api/node/ && pnpm run build && pnpm compile"
     }
-}
+}

examples/todo/node/package.json

@@ -8,6 +8,6 @@
     },
     "scripts": {
         "start": "node .",
-        "prestart": "cd ../../../api/node/ && node build-on-demand.mjs && pnpm compile"
+        "prestart": "cd ../../../api/node/ && pnpm run build && pnpm compile"
     }
-}
+}