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feat: update some samples to show more features
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,29 +1,151 @@ | ||
| function resolveAfter2Seconds(x) { | ||
| return new Promise((resolve) => { | ||
| setTimeout(() => { | ||
| resolve(x); | ||
| }, 2000); | ||
| }); | ||
| } | ||
|
|
||
| // async function expression assigned to a variable | ||
| const add = async function (x) { | ||
| const a = await resolveAfter2Seconds(20); | ||
| const b = await resolveAfter2Seconds(30); | ||
| return x + a + b; | ||
| }; | ||
|
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| add(10).then((v) => { | ||
| console.log(v); // prints 60 after 4 seconds. | ||
| }); | ||
| // --- Demonstration of imports --- | ||
|
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| // Importing named exports and the default export | ||
| import defaultAnimal, { person, add } from './module.js'; | ||
|
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| // Importing everything from the module as an alias | ||
| import * as Module from './module.js'; | ||
|
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|
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| // --- Demonstration of exports --- | ||
|
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| // Named exports | ||
| export const person = { name: "Alice", age: 30 }; | ||
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| export function add(x, y = 0) { | ||
| return x + y; | ||
| } | ||
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| // Default export | ||
| const defaultAnimal = { name: "Default Animal" }; | ||
| export default defaultAnimal; | ||
|
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| // Generator function | ||
| export function* idGenerator() { | ||
| let id = 0; | ||
| while (true) { | ||
| yield id++; | ||
| } | ||
| } | ||
|
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| // Using typeof for runtime type checks | ||
| console.log(typeof person); // object | ||
| console.log(add(2, 3)); // 5 | ||
| console.log(defaultAnimal); // { name: "Default Animal" } | ||
|
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| // Emulating 'satisfies' behavior using runtime checks | ||
| function createAnimal(animal) { | ||
| if (typeof animal.name === 'string') { | ||
| return animal; // Ensures the animal has a 'name' property | ||
| } | ||
| throw new Error("Animal must have a name"); | ||
| } | ||
|
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| const dog = createAnimal({ name: "Buddy", breed: "Golden Retriever" }); | ||
| console.log(dog); // { name: 'Buddy', breed: 'Golden Retriever' } | ||
|
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| // Generator usage | ||
| const generator = Module.idGenerator(); | ||
| console.log(generator.next().value); // 0 | ||
| console.log(generator.next().value); // 1 | ||
| console.log(generator.next().value); // 2 | ||
|
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| // Handling a generic-like behavior by allowing any type and runtime checks | ||
| function identity(arg) { | ||
| return arg; | ||
| } | ||
|
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| let str = identity("Hello"); | ||
| let num = identity(42); | ||
| console.log(str, num); // "Hello", 42 | ||
|
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| // Emulating default generics by using default parameters | ||
| function wrapInArray(value = "") { | ||
| return [value]; | ||
| } | ||
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| const stringArray = wrapInArray(); // Default is empty string | ||
| const numberArray = wrapInArray(42); // Passes 42 explicitly | ||
| console.log(stringArray, numberArray); // [""] , [42] | ||
|
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| // --- for-of and for-in loops --- | ||
|
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| // for-of: Iterates over iterable objects like arrays, strings, maps, etc. | ||
| const fruits = ["apple", "banana", "cherry"]; | ||
| for (const fruit of fruits) { | ||
| console.log(fruit); // Outputs: apple, banana, cherry | ||
| } | ||
|
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||
| // for-in: Iterates over enumerable properties of an object | ||
| const car = { make: "Tesla", model: "Model S", year: 2021 }; | ||
| for (const key in car) { | ||
| if (car.hasOwnProperty(key)) { | ||
| console.log(`${key}: ${car[key]}`); // Outputs key-value pairs of car object | ||
| } | ||
| } | ||
|
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||
| // --- IIFE (Immediately Invoked Function Expression) --- | ||
|
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||
| (function () { | ||
| console.log("This IIFE runs immediately after it's defined."); | ||
| const privateVar = "I'm private inside the IIFE!"; | ||
| console.log(privateVar); // Accessing the private variable inside the IIFE | ||
| })(); | ||
|
|
||
| // --- Using a generator to loop indefinitely --- | ||
| function* infiniteGenerator() { | ||
| let i = 0; | ||
| while (true) { | ||
| yield i++; | ||
| } | ||
| } | ||
|
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| const gen = infiniteGenerator(); | ||
| console.log(gen.next().value); // 0 | ||
| console.log(gen.next().value); // 1 | ||
|
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| // --- Async and Await --- | ||
|
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| async function fetchData(url) { | ||
| try { | ||
| const response = await fetch(url); | ||
| if (!response.ok) { | ||
| throw new Error('Network response was not ok'); | ||
| } | ||
| const data = await response.json(); | ||
| return data; | ||
| } catch (error) { | ||
| console.error('There has been a problem with your fetch operation:', error); | ||
| } | ||
| } | ||
|
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| // Example usage of async function | ||
| fetchData('https://jsonplaceholder.typicode.com/todos/1') | ||
| .then(data => console.log(data)) // Outputs fetched data | ||
| .catch(error => console.error(error)); | ||
|
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| // JSDoc type annotations | ||
| /** | ||
| * @typedef {Object} Task | ||
| * @property {string} title | ||
| * @property {boolean} completed | ||
| */ | ||
|
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| /** | ||
| * Create a task | ||
| * @param {Task} task | ||
| * @returns {Task} | ||
| */ | ||
| function createTask(task) { | ||
| return task; | ||
| } | ||
|
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| // async function expression used as an IIFE | ||
| (async function (x) { | ||
| const p1 = resolveAfter2Seconds(20); | ||
| const p2 = resolveAfter2Seconds(30); | ||
| return x + (await p1) + (await p2); | ||
| })(10).then((v) => { | ||
| console.log(v); // prints 60 after 2 seconds. | ||
| const myTask = createTask({ | ||
| title: "Learn JavaScript", | ||
| completed: false, | ||
| }); | ||
| console.log(myTask); | ||
|
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| // From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/async_function | ||
| // Importing everything as a namespace (simulated for demonstration) | ||
| console.log(Module.person); // { name: "Alice", age: 30 } | ||
| console.log(Module.add(10, 20)); // 30 |
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