hinzugefügt Daten transformation Mithilfe, map(), filter(), reduce() Funktionen

javascript/Javascript Expert/chapter11/dataTransformMapFilterReduce.js

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+const account1 = {
+  owner: "David Aster",
+  movements: [200, 450, -400, 3000, -650, -130, 70, 1300],
+  interestRate: 1.2, // %
+  pin: 1111,
+};
+
+const account2 = {
+  owner: "Joanne Aster",
+  movements: [5000, 3400, -150, -790, -3210, -1000, 8500, -30],
+  interestRate: 1.5,
+  pin: 2222,
+};
+
+const account3 = {
+  owner: "Nika Aster",
+  movements: [200, -200, 340, -300, -20, 50, 400, -460],
+  interestRate: 0.7,
+  pin: 3333,
+};
+
+const account4 = {
+  owner: "Eva Aster",
+  movements: [430, 1000, 700, 50, 90],
+  interestRate: 1,
+  pin: 4444,
+};
+
+const randomNumbers = function (n) {
+  let arr = [];
+  for (let i = 0; i < n; i++) {
+    arr.push(Math.trunc(Math.random() * 1000));
+  }
+  return arr;
+};
+console.log("Ursprüngliche Werte");
+var arr = randomNumbers(20);
+// werden ursprüngliche Werte geändert, in unserem Fall curr * 2
+console.log(arr);
+arr = arr.map(function (curr) {
+  return curr * 2;
+});
+console.log("Geänderte Werte (map)");
+console.log(arr);
+
+arr = randomNumbers(20);
+// Predikat in der return Anweisung, damit werden Werte, die der Bedienung nicht entsprechen, aus dem Feld enfernt
+console.log("Ursprüngliche Werte");
+console.log(arr);
+arr = arr.filter(function (value) {
+  return value > 450;
+});
+console.log("Geänderte Werte (filter > 450)");
+console.log(arr);
+
+arr = randomNumbers(20);
+console.log("Ursprüngliche Werte");
+console.log(arr);
+// Berechnung aller Werte
+arr = arr.reduce(function (prev, curr) {
+  return prev + curr;
+});
+// Array wird in einen Wert konvertiert
+console.log(arr);
+
+const user = "David Steven Schmidt Aster";
+// Abkürzung der Namen Mithilfe string Funtionen (Function chaining)
+const createUsername = function (user) {
+  return user
+    .toLowerCase()
+    .split(" ")
+    .map(name => name[0])
+    .join("");
+};
+console.log(createUsername(user));
+
+const accounts = [account1, account2, account3, account4];
+
+const createUsernames = function (accounts) {
+  accounts.forEach(function (account) {
+    account.username = account.owner
+      .toLowerCase()
+      .split(" ")
+      .map(name => name[0])
+      .join("");
+  });
+};
+
+createUsernames(accounts);
+console.log(accounts);

javascript/Javascript Expert/chapter11/forEachWithMaps.js

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+const currencies = new Map([
+  ["USD", "United States dollar"],
+  ["EUR", "Euro"],
+  ["GBP", "Pound sterling"],
+]);
+
+currencies.forEach(function (value, key, map) {
+  console.log(`${key}: ${value}`);
+});
+
+const currency1 = new Set(["USD", "EUR", "GBP"]);
+currency1.forEach(function (key, value, set) {
+  console.log(`${key}: ${value} `);
+});

javascript/Javascript Expert/chapter11/map.js

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+const randomNumbers = n => {
+  let arr = [];
+  for (let i = 0; i < n; i++) {
+    arr.push(Math.trunc(Math.random() * 1000));
+  }
+  return arr;
+};
+var arr = randomNumbers(15);
+console.log("EUR", arr);
+
+const eurToUsd = 1.2;
+arr = arr.map(that => Math.trunc(that * eurToUsd));
+console.log("Konvertiert ins USD", arr);