add playground for contrib faster local prototyping

eslint things

Author: zardoy

.eslintignore

@@ -1,3 +1,4 @@
 # ignore files that have typescript import
 typescript/**
 src/configurationType.ts
+playground.ts

buildTsPlugin.mjs

@@ -30,4 +30,4 @@ export const buildTsPlugin = async (/** @type {string} */ outDir, /** @type {str
 }
 
 const name = 'typescript-essential-plugins'
-buildTsPlugin(`out/node_modules/${name}`, name, 'typescript/src/index.ts')
+await buildTsPlugin(`out/node_modules/${name}`, name, 'typescript/src/index.ts')

playground.ts

@@ -0,0 +1,38 @@
+//@ts-check
+import ts from 'typescript/lib/tsserverlibrary'
+import { createLanguageService } from './typescript/src/dummyLanguageService'
+
+let testString = 'const a: {/** @default test */a: 5} | {b: 6, /** yes */a: 9} = null as any;\nif ("||" in a) {}'
+const replacement = '||'
+const pos = testString.indexOf(replacement)
+testString = testString.slice(0, pos) + testString.slice(pos + replacement.length)
+const filePath = '/test.ts'
+const languageService = createLanguageService({
+    [filePath]: testString,
+})
+
+const program = languageService.getProgram()
+const sourceFile = program?.getSourceFile(filePath)
+if (!program || !sourceFile) throw new Error('No source file')
+
+const typeChecker = program.getTypeChecker()
+const node = findChildContainingPosition(ts, sourceFile, pos)
+if (!node) throw new Error('No node')
+const type = typeChecker.getTypeAtLocation(node)
+
+// explore:
+
+console.log(typeChecker.typeToString(type))
+
+function findChildContainingPosition(
+    typescript: typeof import('typescript/lib/tsserverlibrary'),
+    sourceFile: ts.SourceFile,
+    position: number,
+): ts.Node | undefined {
+    function find(node: ts.Node): ts.Node | undefined {
+        if (position >= node.getStart() && position < node.getEnd()) return typescript.forEachChild(node, find) || node
+
+        return
+    }
+    return find(sourceFile)
+}

typescript/src/dummyLanguageService.ts

@@ -0,0 +1,20 @@
+// only for basic testing, as vscode is actually using server
+import ts from 'typescript/lib/tsserverlibrary'
+
+export const createLanguageService = (files: Record<string, string>) => {
+    const dummyVersion = '1'
+    const languageService = ts.createLanguageService({
+        getProjectVersion: () => dummyVersion,
+        getScriptVersion: () => dummyVersion,
+        getCompilationSettings: () => ({ allowJs: true, jsx: ts.JsxEmit.Preserve }),
+        getScriptFileNames: () => Object.keys(files),
+        getScriptSnapshot: fileName => {
+            const contents = files[fileName]
+            if (contents === undefined) return
+            return ts.ScriptSnapshot.fromString(contents)
+        },
+        getCurrentDirectory: () => '',
+        getDefaultLibFileName: () => 'defaultLib:lib.d.ts',
+    })
+    return languageService
+}