You don’t need dotenv (and I doubt that library will work at runtime in a client-side application anyway). create-react-app actually provides this functionality out of the box, assuming you’re using react-scripts@0.5.0 or higher. The steps are as follows: Create a .env file in the root of your project. Add a variable, starting with the prefix … Read more
Array.from() is a nice way to do this. You can pass a {length: somlength} object or some other array-like object and a function that defines each item. The first argument (calling it _ just to indicate it’s not used) to that function would be the item from an array we passed in (but we only … Read more
Yep – works in all loops. const myObject = { propA: ‘foo’, propB: ‘bar’ }; for (let propName in myObject) { console.log(propName); if (propName !== ‘propA’) { continue; } else if (propName === ‘propA’) { break; } } (By loops I mean for, for…in, for…of, while and do…while, not forEach, which is actually a function … Read more
Update: All this info and more has now been added to the Jest docs in a new guide, “ES6 Class Mocks.” Full disclosure: I wrote it. 🙂 The key to mocking ES6 classes is knowing that an ES6 class is a function. Therefore, the mock must also be a function. Call jest.mock(‘./mocked-class.js’);, and also import … Read more
export should be static. For conditional exports CommonJS modules and exports can be used. It should be handled with ES6 modules this way: export let Foo; if (window.Foo === undefined) { Foo = class Foo { … } } else { Foo = window.Foo; } For platform-independent solution (this may not be equal to global … Read more
Yes, it is that simple. In your example with Object.create/Object.assign, you are using a factory function to create new instances of duck (similar to the way jQuery creates new instances if you select an element with var body = $(‘body’)). An advantage of this code style is, that it doesn’t force you to call a … Read more
Note that the Babel translation is assuming strict mode, but your result with window indicates you’re running your code in loose mode. If you tell Babel to assume loose mode, its transpilation is different: var _this = this; // ** var arrowObject = { name: ‘arrowObject’, printName: function printName() { console.log(_this); // ** } }; … Read more
http://eslint.org/docs/rules/consistent-return says: This rule requires return statements to either always or never specify values. When your if-condition is not met, the arrow function will terminate without encountering a return statement, which violates this rule. Your second version violates this rule because your second return does not specify a value, contrary to the first return. The … Read more
Destructuring is just a nice way to unpack properties from objects and arrays and assign them to variables. As the trasnpiled code in the question suggests, any kind of operation is not possible. One hack would be to create 2 more variables (which don’t exist in input) and set the default value to the number … Read more
You can assign new variable names, like shown in this MDN Example var o = { p: 42, q: true }; // Assign new variable names var { p: foo, q: bar } = o; console.log(foo); // 42 console.log(bar); // true So, in your case, the code will be like this const b = 6; … Read more