This helps make your code more succinct – since props is an object, the spread operator takes the properties of the object you pass in and applied them to the component. So the Component will have properties a foo with a value of x and a bar with a value of y. It would be … Read more
Presumably component/Data and actions/Data both have default exports rather than named exports? Like this: export default class Data {} If that’s the case, then the importer can call the variables whatever they like: import Data1 from ‘component/Data.js’; import Data2 from ‘actions/Data.js’; If they are named exports: export class Data {} Then you need to use … Read more
Only methods can be spied. There is no way to spy on funcB if it’s called directly like funcB() within same module. In order for exported function to be spied or mocked, funcA and funcB should reside in different modules. This allows to spy on funcB in transpiled ES module (module object is read-only in … Read more
If the let keyword introduces a proper implementation of block scope, does var any longer have a use case? There could be one use case: let declarations in global scope don’t create a property on the global object. Example: “use strict”; // for chrome var foo = 42; let bar = 21; console.log(‘window.foo (var)’, window.foo); … Read more
Nearly. It does however depend on how you are exporting them. named exports (export var batz = …): import {batz as Bar} from ‘foo’; default-exported object (export default {batz: …};) – should not be used: import Foo from ‘foo’; var Bar = Foo.batz;
console.log(‘last’, [1, 3, 4, 5].slice(-1)); console.log(‘second_to_last’, [1, 3, 4, 5].slice(-2));
From my answer to another question, this can be simpler: The only requirement is to configure your test environment to Babel, and add the ECMAScript 6 transform plugin: Step 1: Add your test environment to .babelrc in the root of your project: { “env”: { “test”: { “plugins”: [“@babel/plugin-transform-modules-commonjs”] } } } Step 2: Install the … Read more
If you want CommonJS export behavior, you’ll need to use CommonJS directly (or use the plugin in the other answer). This behavior was removed because it caused confusion and lead to invalid ES6 semantics, which some people had relied on e.g. export default { a: ‘foo’ }; and then import {a} from ‘./foo’; which is … Read more