make handlers await async

.gitignore

@@ -3,3 +3,4 @@ yarn.lock
 .nyc_output
 coverage
 .DS_Store
+dist/

dist/index.d.ts

@@ -1,5 +1,5 @@
 /// <reference types="node" />
-import { EventEmitter } from 'events';
+import { EventEmitter2 } from 'eventemitter2';
 import { TextFileDiffOption } from './types';
 import stream from 'stream';
 export declare class StreamLineReader {
@@ -14,7 +14,7 @@ export declare class StreamLineReader {
 /**
  * line by line diff of two files
  */
-export default class TextFileDiff extends EventEmitter {
+export default class TextFileDiff extends EventEmitter2 {
     options: TextFileDiffOption;
     constructor(options?: TextFileDiffOption);
     /**

package.json

@@ -14,7 +14,7 @@
     "npm": ">=6"
   },
   "scripts": {
-    "build": "tsc",
+    "prepare": "mkdir -p dist/ && tsc",
     "test": "tsc && cross-env DEBUG=text-file-diff xo && cross-env DEBUG=text-file-diff nyc ava",
     "report": "tsc && cross-env DEBUG=text-file-diff nyc report --reporter=html"
   },
@@ -57,5 +57,8 @@
   },
   "ava": {
     "failWithoutAssertions": true
+  },
+  "dependencies": {
+    "eventemitter2": "^6.4.4"
   }
 }

src/index.ts

@@ -1,7 +1,7 @@
-import {EventEmitter} from 'events';
+import {EventEmitter2} from 'eventemitter2';
 import {TextFileDiffOption} from './types';
-import {PathLike, createReadStream} from 'fs';
-import {Interface, createInterface} from 'readline';
+import {createReadStream} from 'fs';
+import {createInterface} from 'readline';
 import stream from 'stream';
 
 // import myDebug = require('debug');
@@ -46,7 +46,7 @@ export class StreamLineReader {
 /**
  * line by line diff of two files
  */
-export default class TextFileDiff extends EventEmitter {
+export default class TextFileDiff extends EventEmitter2 {
   options: TextFileDiffOption;
 
   constructor(options?: TextFileDiffOption) {
@@ -101,29 +101,31 @@ export default class TextFileDiff extends EventEmitter {
     // debug(line1, line1, cmpar);
     // debug(lineReader1.nextValue, lineReader2.nextValue, 'next', lineReader1.eof, lineReader2.eof);
     // emit on compared
-    this.emit('compared', line1, line2, cmpar, lineReader1, lineReader2);
+    await this.emitAsync('compared', line1, line2, cmpar, lineReader1, lineReader2);
 
     if (cmpar > 0) {
       // line1 > line2: new line detected
       // if file2 ended before file1, then file2 lost line1
       // else file2 has new line
-      if (lineReader2.eof > lineReader1.eof) {
-        this.emit('-', line1, lineReader1, lineReader2);
-      } else {
-        this.emit('+', line2, lineReader1, lineReader2);
-      }
+
+      /* eslint-disable @typescript-eslint/no-unused-expressions */
+      lineReader2.eof > lineReader1.eof ?
+        await this.emitAsync('-', line1, lineReader1, lineReader2) :
+        await this.emitAsync('+', line2, lineReader1, lineReader2);
+      /* eslint-enable @typescript-eslint/no-unused-expressions */
 
       // incr File2 to next line
       await lineReader2.moveNext();
     } else if (cmpar < 0) {
       // line1 < line2: deleted line
       // if file1 ended before file2, then file2 has new line
       // else file1 lost a line
-      if (lineReader1.eof > lineReader2.eof) {
-        this.emit('+', line2, lineReader1, lineReader2);
-      } else {
-        this.emit('-', line1, lineReader1, lineReader2);
-      }
+
+      /* eslint-disable @typescript-eslint/no-unused-expressions */
+      lineReader1.eof > lineReader2.eof ?
+        await this.emitAsync('+', line2, lineReader1, lineReader2) :
+        await this.emitAsync('-', line1, lineReader1, lineReader2);
+      /* eslint-enable @typescript-eslint/no-unused-expressions */
 
       // incr File1 to next line
       await lineReader1.moveNext();

tests/index.js

@@ -35,6 +35,29 @@ test('test skip header', async t => {
   t.is(actual, expected);
 });
 
+test('test await listener', async t => {
+  const m = new TextFileDiff();
+  const expected = 'compared+compared+comparedcompared+compared-compared-comparedcompared+';
+
+  let actual = '';
+
+  const getListenerFor = event => async () => new Promise(resolve => {
+    setTimeout(() => {
+      actual += event;
+      resolve();
+    }, 200);
+  });
+
+  m.on('-', getListenerFor('-'));
+  m.on('+', getListenerFor('+'));
+
+  m.on('compared', getListenerFor('compared'));
+
+  await m.diff('tests/file1.txt', 'tests/file2.txt');
+
+  t.is(actual, expected);
+});
+
 test('test against null or empty file', async t => {
   let expected = '-some,csv,data\n';