Extended – to provide more details based on some comments The error Error TS2306: File ‘test.ts’ is not a module. Comes from the fact described here http://exploringjs.com/es6/ch_modules.html 17. Modules This chapter explains how the built-in modules work in ECMAScript 6. 17.1 Overview In ECMAScript 6, modules are stored in files. There is exactly one module … Read more
Use jest.requireActual() inside jest.mock() jest.requireActual(moduleName) Returns the actual module instead of a mock, bypassing all checks on whether the module should receive a mock implementation or not. Example I prefer this concise usage where you require and spread within the returned object: // myModule.test.js import { otherFn } from ‘./myModule.js’ jest.mock(‘./myModule.js’, () => ({ …(jest.requireActual(‘./myModule.js’)), … Read more
someClassInstance.constructor.name is exactly the correct way to do this. Transpilers may not support this, but it is the standard way per the specification. (The name property of functions declared via ClassDeclaration productions is set in 14.5.15, step 6.)
it is because you are rendering the form in a function inside render(). Every time your state/prop change, the function returns a new form. it caused you to lose focus. Try putting what’s inside the function into your render directly. <main id=”main” role=”main”> <div className=”container-fluid”> <FormPostSingle /> </div> </main> ===> <main id=”main” role=”main”> <div className=”container-fluid”> … Read more
Check my example below, super method working as expected. Using a few tricks even instanceof works (most of the time): // base class class A { foo() { console.log(`from A -> inside instance of A: ${this instanceof A}`); } } // B mixin, will need a wrapper over it to be used const B = … Read more
This is good for shallow cloning. The object spread is a standard part of ECMAScript 2018. For deep cloning you’ll need a different solution. const clone = {…original} to shallow clone const newobj = {…original, prop: newOne} to immutably add another prop to the original and store as a new object.
In ES6, imports are live read-only views on exported-values. As a result, when you do import a from “somemodule”;, you cannot assign to a no matter how you declare a in the module. However, since imported variables are live views, they do change according to the “raw” exported variable in exports. Consider the following code … Read more
ES2015 does not have Java-style classes with built-in affordances for your desired design pattern. However, it has some options which may be helpful, depending on exactly what you are trying to accomplish. If you would like a class that cannot be constructed, but whose subclasses can, then you can use new.target: class Abstract { constructor() … Read more
The documentation states: …constant cannot change through re-assignment …constant cannot be re-declared When you’re adding to an array or object you’re not re-assigning or re-declaring the constant, it’s already declared and assigned, you’re just adding to the “list” that the constant points to. So this works fine: const x = {}; x.foo = ‘bar’; console.log(x); … Read more
let and const have two broad differences from var: They are block scoped. Accessing a var before it is declared has the result undefined; accessing a let or const before it is declared throws ReferenceError: console.log(aVar); // undefined console.log(aLet); // Causes ReferenceError: Cannot access ‘aLet’ before initialization var aVar = 1; let aLet = 2; … Read more