Ensure certain paths are always in gitignore

programs/create/module.ts

@@ -9,6 +9,7 @@ import {installDependencies} from './steps/install-dependencies'
 import {writeReadmeFile} from './steps/write-readme-file'
 import {writeManifestJson} from './steps/write-manifest-json'
 import {generateExtensionTypes} from './steps/generate-extension-types'
+import {writeGitignore} from './steps/write-gitignore'
 import {initializeGitRepository} from './steps/initialize-git-repository'
 
 export interface CreateOptions {
@@ -53,6 +54,7 @@ export async function extensionCreate(
     await writeReadmeFile(projectPath, projectName)
     await writeManifestJson(projectPath, projectName)
     await initializeGitRepository(projectPath, projectName)
+    await writeGitignore(projectPath)
 
     if (utils.isTypeScriptTemplate(template)) {
       await generateExtensionTypes(projectPath, projectName)

programs/create/steps/write-gitignore.ts

@@ -0,0 +1,38 @@
+import fs from 'fs/promises'
+
+const globalLines = ['/dist', 'extension.d.ts']
+
+export async function writeGitignore(projectPath: string) {
+  const gitIgnorePath = projectPath + '/.gitignore'
+
+  const fileHandle = await fs.open(gitIgnorePath, 'a+').catch((err) => {
+    console.error(err)
+    process.exit(1)
+  })
+
+  const paths = new Set<String>()
+  // autoClose is required, otherwise the stream will close the file
+  // and we'll be unable to append to it
+  //
+  // Note: while readLines works for this use-case, care needs to be had
+  // if adding more contents to the loop, basically, the loop should just
+  // consume the data from readLines and nothing else
+  //
+  // Reference: https://stackoverflow.com/a/70616910
+  for await (let line of fileHandle.readLines({autoClose: false})) {
+    line = line.trim()
+    if (line.length === 0 || line.startsWith('#')) {
+      continue
+    }
+    paths.add(line)
+  }
+
+  const linesToAdd = globalLines.filter((line) => !paths.has(line))
+
+  await fileHandle
+    .appendFile(linesToAdd.join('\n'), {flush: true})
+    .catch((err) => {
+      console.error(err)
+      process.exit(1)
+    })
+}