練習問題解答

app.js

@@ -1,11 +1,22 @@
 'use strict';
 const fs = require('fs');
 const fileName = './test.txt';
-for (let count = 0; count < 500; count++) {
-  fs.appendFile(fileName, 'あ', 'utf8', () => {});
-  fs.appendFile(fileName, 'い', 'utf8', () => {});
-  fs.appendFile(fileName, 'う', 'utf8', () => {});
-  fs.appendFile(fileName, 'え', 'utf8', () => {});
-  fs.appendFile(fileName, 'お', 'utf8', () => {});
-  fs.appendFile(fileName, '\n', 'utf8', () => {});
-}
+
+function appendFilePromise(fileName, str) {
+  return new Promise((resolve) => {
+    fs.appendFile(fileName, str, 'utf8', () => resolve());
+  });
+}
+
+async function main() {
+  for (let count = 0; count < 500; count++) {
+    await appendFilePromise(fileName, 'あ');
+    await appendFilePromise(fileName, 'い');
+    await appendFilePromise(fileName, 'う');
+    await appendFilePromise(fileName, 'え');
+    await appendFilePromise(fileName, 'お');
+    await appendFilePromise(fileName, '\n');
+  }
+}
+
+main();

app2.js

@@ -0,0 +1,8 @@
+'use strict';
+const fs = require('fs');
+const fileName = './test.txt';
+for (let count = 0; count < 30; count++) {
+  fs.appendFileSync(fileName, 'おはようございます\n', 'utf8', () => {});
+  fs.appendFileSync(fileName, 'こんにちは\n', 'utf8', () => {});
+  fs.appendFileSync(fileName, 'こんばんは\n', 'utf8', () => {});
+}

promis-test.js

@@ -0,0 +1,24 @@
+'use strict';
+
+new Promise((resolve) => {
+    const nowDate = new Date();
+    resolve(nowDate);
+}).then((v1) => {
+    //V1は現在の時刻情報
+    const monthAndDate = {
+        month: v1.getMonth(),
+        date: v1.getDate()
+    }
+    return new Promise((resolve) => {
+        resolve(monthAndDate);
+    });
+}).then((v2) => {
+    //v2は日付の情報
+    const text = `今日は${v2.month + 1}月${v2.date}日です。`;
+    return new Promise((resolve) => {
+        resolve(text)
+    });
+}).then((v3) => {
+    //v3は日付を示す文章
+    console.log(v3);//今日の日付に関する文章
+});