Shorten minified error URL

Author: kubk

.changeset/fix-minified-error-link.md

@@ -0,0 +1,5 @@
+---
+"mobx": patch
+---
+
+Shorten minified error URL to reduce production bundle size.

.gitignore

@@ -6,6 +6,7 @@ coverage
 test/babel-tests.js
 test/typescript/typescript-tests.js
 dist/
+/docs/errors.md
 **/.idea/*
 !/.idea/icon.png
 !/.idea/vcs.xml

packages/mobx/src/errors.ts

@@ -87,7 +87,7 @@ export function die(error: string | keyof typeof errors, ...args: any[]): never
         typeof error === "number"
             ? `[MobX] minified error nr: ${error}${
                   args.length ? " " + args.map(String).join(",") : ""
-              }. Find the full error at: https://github.com/mobxjs/mobx/blob/main/packages/mobx/src/errors.ts`
+              }. See http://mobx.js.org/errors`
             : `[MobX] ${error}`
     )
 }

website/i18n/en.json

@@ -64,6 +64,10 @@
         "title": "Decorators",
         "sidebar_label": "Decorators {🚀}"
       },
+      "errors": {
+        "title": "MobX error codes",
+        "sidebar_label": "Error codes"
+      },
       "faq/migrate-to-6": {
         "title": "Migrating from MobX 4/5"
       },

website/package.json

@@ -1,7 +1,9 @@
 {
   "scripts": {
     "examples": "docusaurus-examples",
+    "prestart": "node scripts/generate-error-docs.mjs",
     "start": "docusaurus-start",
+    "prebuild": "node scripts/generate-error-docs.mjs",
     "build": "docusaurus-build",
     "publish-gh-pages": "docusaurus-publish",
     "write-translations": "docusaurus-write-translations",

website/scripts/generate-error-docs.mjs

@@ -0,0 +1,80 @@
+#!/usr/bin/env node
+
+import { readFileSync, writeFileSync } from "node:fs"
+import { relative } from "node:path"
+import { fileURLToPath } from "node:url"
+import { runInNewContext } from "node:vm"
+
+const repoRoot = fileURLToPath(new URL("../..", import.meta.url))
+const errorsPath = fileURLToPath(new URL("../../packages/mobx/src/errors.ts", import.meta.url))
+const outputPath = fileURLToPath(new URL("../../docs/errors.md", import.meta.url))
+
+function readNiceErrors() {
+    const source = readFileSync(errorsPath, "utf8")
+    const match = source.match(/const niceErrors = ([\s\S]*?) as const/)
+
+    if (!match) {
+        throw new Error(`Could not find niceErrors in ${errorsPath}`)
+    }
+
+    const objectLiteral = match[1].replace(": PropertyKey", "")
+    return runInNewContext(`(${objectLiteral})`, Object.create(null), { timeout: 1000 })
+}
+
+function placeholder(name) {
+    return {
+        constructor: {
+            name: `{${name}.constructor.name}`
+        },
+        toString() {
+            return `{${name}}`
+        }
+    }
+}
+
+function getParamNames(fn) {
+    const match = fn.toString().match(/^[^(]*\(([^)]*)\)/)
+    return match ? match[1].split(",").map(name => name.trim()).filter(Boolean) : []
+}
+
+function renderMessage(message) {
+    if (typeof message !== "function") {
+        return message
+    }
+
+    return message(...getParamNames(message).map(placeholder))
+}
+
+function escapeMarkdownTableCell(value) {
+    return String(value).replace(/\r?\n/g, "<br />").replace(/\|/g, "\\|")
+}
+
+function renderDocs(errors) {
+    const rows = Object.keys(errors)
+        .sort((left, right) => Number(left) - Number(right))
+        .map(code => `| ${code} | ${escapeMarkdownTableCell(renderMessage(errors[code]))} |`)
+        .join("\n")
+
+    return `---
+title: MobX error codes
+sidebar_label: Error codes
+hide_title: true
+custom_edit_url: https://github.com/mobxjs/mobx/edit/main/packages/mobx/src/errors.ts
+---
+
+<script async type="text/javascript" src="//cdn.carbonads.com/carbon.js?serve=CEBD4KQ7&placement=mobxjsorg" id="_carbonads_js"></script>
+
+# MobX error codes
+
+In development builds, MobX throws full error messages. Production builds replace known messages with short numeric codes to keep the published bundle small.
+
+| Code | Message |
+| ---- | ------- |
+${rows}
+`
+}
+
+const docs = renderDocs(readNiceErrors())
+writeFileSync(outputPath, docs)
+
+console.log(`Generated ${relative(repoRoot, outputPath)} from ${relative(repoRoot, errorsPath)}`)

website/sidebars.json

@@ -22,6 +22,7 @@
       "understanding-reactivity",
       "subclassing",
       "analyzing-reactivity",
+      "errors",
       "computeds-with-args",
       "mobx-utils",
       "custom-observables",