perf: use type definitions for prettier

package.json

@@ -77,6 +77,7 @@
     "watch": "tsc -watch -p ./"
   },
   "dependencies": {
+    "@types/prettier": "^1.15.1",
     "prettier": "^1.15.2"
   },
   "devDependencies": {

src/scssFormatterProvider.ts

@@ -1,24 +1,27 @@
+import {
+  BuiltInParserName,
+  format,
+  Options as PrettierOptions
+} from 'prettier';
 import {
   DocumentFormattingEditProvider, Position, Range, TextDocument,
   TextEdit, workspace, WorkspaceConfiguration
 } from 'vscode';
 
-const prettier = require('prettier');
-
 import { safeExecution } from './errorHandler';
 
-async function format(document: TextDocument): Promise<string> {
+async function formatDocument(document: TextDocument): Promise<string> {
   const workspaceConfiguration: WorkspaceConfiguration = workspace.getConfiguration('scssFormatter');
   const rawDocumentText = document.getText();
   const { fileName, languageId } = document;
 
-  const options = {
+  const options: PrettierOptions = {
     ...Object.assign({}, workspaceConfiguration),
-    parser: languageId
+    parser: languageId as BuiltInParserName
   };
 
   return safeExecution(
-    () => prettier.format(rawDocumentText, options),
+    () => format(rawDocumentText, options),
     rawDocumentText,
     fileName
   );
@@ -33,7 +36,7 @@ function fullDocumentRange(document: TextDocument): Range {
 
 export class SCSSFormatter implements DocumentFormattingEditProvider {
   public async provideDocumentFormattingEdits(document: TextDocument): Promise<TextEdit[]> {
-    const formattedDocument = await format(document);
+    const formattedDocument = await formatDocument(document);
     return [TextEdit.replace(fullDocumentRange(document), formattedDocument)];
   }
 }

src/test/extension.test.ts

@@ -1,10 +1,9 @@
 /* tslint:disable: no-console */
 import * as assert from 'assert';
 import * as path from 'path';
+import { format } from 'prettier';
 import { commands, Uri, window, workspace } from 'vscode';
 
-const prettier = require('prettier');
-
 // activate the formatter
 async function activateFormatter() {
   await commands.executeCommand('scss-formatter.activate');
@@ -25,7 +24,7 @@ async function clearOutput() {
  * @param base base URI
  * @returns source code and resulting code
  */
-async function format(
+async function formatWithVscode(
   file: string,
   base: Uri = workspace.workspaceFolders![0].uri
 ): Promise<{
@@ -53,9 +52,9 @@ async function format(
  * @param file path relative to workspace root
  */
 async function formatSameAsPrettier(file: string) {
-  const result = await format(file);
+  const result = await formatWithVscode(file);
   if (result) {
-    const prettierFormatted = prettier.format(result.source, {
+    const prettierFormatted = format(result.source, {
       filepath: file,
     });
     assert.equal(result.result, prettierFormatted);

src/utils.ts

@@ -1,3 +1,4 @@
+import { BuiltInParserName } from 'prettier';
 import { DocumentSelector, extensions } from 'vscode';
 
 /**
@@ -12,7 +13,7 @@ function getExtensionVersion(): string | null {
 }
 
 /** languages supported by scss formatter */
-const supportedLanguages: string[] = [
+const supportedLanguages: BuiltInParserName[] = [
   'css',
   'scss'
 ];

tsconfig.json

@@ -4,7 +4,7 @@
     "target": "es6",
     "outDir": "out",
     "lib": [
-      "es6"
+      "es2016"
     ],
     "sourceMap": true,
     "rootDir": "src",