gatsby-starter-blogをtypescript化

$ gatsby new example-blog https://github.com/gatsbyjs/gatsby-starter-blog
$ yarn add typescript gatsby-plugin-ts
$ yarn tsc --init

    },
+   `gatsby-plugin-ts`,
    // this (optional) plugin enables Progressive Web App + Offline functionality
    // To learn more, visit: https://gatsby.dev/offline
    // `gatsby-plugin-offline`,
  ],

@@ -4,17 +4,19 @@

     /* Basic Options */
     // "incremental": true,                   /* Enable incremental compilation */
-    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */
-    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
-    // "lib": [],                             /* Specify library files to be included in the compilation. */
-    // "allowJs": true,                       /* Allow javascript files to be compiled. */
+    "target": "ESNext" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */,
+    "module": "ESNext" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */,
+    "lib": [
+      "dom"
+    ] /* Specify library files to be included in the compilation. */,
+    "allowJs": true /* Allow javascript files to be compiled. */,
     // "checkJs": true,                       /* Report errors in .js files. */
-    // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
+    "jsx": "preserve" /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */,
     // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
     // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
     // "sourceMap": true,                     /* Generates corresponding '.map' file. */
     // "outFile": "./",                       /* Concatenate and emit output to single file. */
-    // "outDir": "./",                        /* Redirect output structure to the directory. */
+    "outDir": "./build" /* Redirect output structure to the directory. */,
     // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
     // "composite": true,                     /* Enable project compilation */
     // "tsBuildInfoFile": "./",               /* Specify file to store incremental compilation information */
@@ -25,7 +27,7 @@
     // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */

     /* Strict Type-Checking Options */
-    "strict": true,                           /* Enable all strict type-checking options. */
+    // "strict": true,                        /* Enable all strict type-checking options. */
     // "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
     // "strictNullChecks": true,              /* Enable strict null checks. */
     // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
@@ -41,14 +43,14 @@
     // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */

     /* Module Resolution Options */
-    // "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
+    "moduleResolution": "node" /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */,
     // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
     // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
     // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
     // "typeRoots": [],                       /* List of folders to include type definitions from. */
     // "types": [],                           /* Type declaration files to be included in compilation. */
     // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
-    "esModuleInterop": true,                  /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
+    "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */,
     // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
     // "allowUmdGlobalAccess": true,          /* Allow accessing UMD globals from modules. */

@@ -63,7 +65,7 @@
     // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */

     /* Advanced Options */
-    "skipLibCheck": true,                     /* Skip type checking of declaration files. */
-    "forceConsistentCasingInFileNames": true  /* Disallow inconsistently-cased references to the same file. */
+    "skipLibCheck": true /* Skip type checking of declaration files. */,
+    "forceConsistentCasingInFileNames": true /* Disallow inconsistently-cased references to the same file. */
   }
 }

$ echo 'declare const __PATH_PREFIX__: string' > src/global.d.ts