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Following is a very simple unit test which verifies if the add() function works correctly. While the test works, but it does not follow the AAA(Arrange, Act, Assert) pattern. import {it, expect} from 'vitest'; import { add } from './math'; it('should summarize all number values in an array', ()=>{ const result = add([1,2,3]) expect(result).toBe(6) }); Question: What is AAA (Arrange, Act, Assert) pattern in testing? AAA pattern allows you to write unit tests which are more readable and maintainable in long term....

Modules ES6 has added Modules to JavaScript. This means, that you may split up your code over multiple files, which of course is a good practice. This is common in ES6 already, however you always require a module loader for that. To split up your code, you basically export variables, functions, objects, … in one file and import it in another: // export.js export let myExportedVar = 42; // import.js import { myExportedVar } from '....

There are two important Rules, which you need to understand if you’re working with ES6 Modules: Modules are always in Strict Mode (no need to define "use strict"). Modules don’t have a shared, global Scope. Instead each Module has its own Scope.

Destructuring is a cool new feature which allows you to easily extract values from an object or an array. It is important to note, that destructuring for arrays is position based, whereas in case of the objects it is based on the names of the keys. Array: let numbers = [1, 2, 3, 4, 5]; let [a, b] = numbers;// a => 1, b => 2 Object: let person = { name: 'Max', age: 27 }; let {name, age} = person; // Notice the {} instead of [] More information may be found here....

ES6 added two important new operators: Rest and Spread. Technically they look the same ( ... => three dots) but they are used in different places. Rest: function sumUp(start, ...toAdd) {} Transforms a list of arguments (1, 2, 3) into an array ([1, 2, 3]) which may be used inside the function. This behavior is triggered when used inside of a function argument list. Spread: let ids = [1, 2, 3, 4, 5, 6]; console....