いくつかの型サンプルを追加

Author: tksgtkm

js_ts_sample/src/ts/type_programming/basic_type/function_total.ts

@@ -0,0 +1,25 @@
+type Item = {
+    name: string,
+    price: number
+};
+
+const getTotal = (items: Item[]): number => {
+    let total: number = 0;
+
+    for (let item of items) {
+        total += item.price;
+    }
+
+    return total;
+}
+
+let total: number = getTotal(
+    [
+        {name: 'Cherry gum', price: 0.10},
+        {name: 'Mint gum', price: 0.10},
+        {name: 'Strawberry gum', price: 0.10}
+    ]
+);
+
+console.log(total)
+console.log(total == 0.30)

js_ts_sample/src/ts/type_programming/basic_type/gatekeeper.ts

@@ -0,0 +1,13 @@
+declare function secondsSinceLastComment(userId: string): number;
+declare function postComment(comment: string, userId: string): void;
+
+const commentGatekeeper = (comment: string, userId: string): boolean => {
+    if ((comment == "") || (secondsSinceLastComment(userId) < 10))
+        return false;
+
+    postComment(comment, userId);
+
+    return true;
+}
+
+console.log(commentGatekeeper('so good', '12'));

js_ts_sample/src/ts/type_programming/basic_type/logging_error.ts

@@ -0,0 +1,16 @@
+const fs = require("fs");
+
+
+const raise = (message: string): never => {
+    console.log(`Error "${message}" raised at ${new Date()}`);
+    throw new Error(message);
+}
+
+const readCOnfig = (configFile: string): string => {
+    if (!fs.existsSync(configFile))
+        raise(`Configration file ${configFile} missing`);
+
+    return fs.readFileSync(configFile, "utf-8");
+}
+
+console.log(readCOnfig('test.ini'))

js_ts_sample/src/ts/type_programming/basic_type/unit_type.ts

@@ -0,0 +1,15 @@
+
+declare const UnitType: unique symbol;
+
+class Unit {
+    [UnitType]: void | undefined;
+    static readonly value: Unit = new Unit();
+    private constructor() {};
+}
+
+const greet = (): Unit => {
+    console.log('Hello');
+    return Unit.value;
+}
+
+console.log(greet());

js_ts_sample/src/ts/type_programming/composable.ts

@@ -0,0 +1,21 @@
+const first = <T>(range: T[], p: (elem: T) => boolean): T | undefined => {
+    for (let elem of range) {
+        if (p (elem)) {
+            return elem;
+        }
+    }
+}
+
+const findFirstNegativeNumber = (numbers: number[]): number | undefined => {
+    return first(numbers, n => n < 0);
+}
+
+const findFirstOneCharacterString = (strings: string[]): string | undefined => {
+    return first(strings, str => str.length == 1);
+}
+
+const numbers = [1, -2, 3, -4, 5]
+console.log(findFirstNegativeNumber(numbers));
+
+const strings = ['aaa', 'dfjdf', 'd', 'dfd', 'a', 'ddd'];
+console.log(findFirstOneCharacterString(strings));