We talked about this in the TC39 face-to-face meetings and it is deliberate that we don’t expose a way to detect whether a function is a generator or not. The reason is that any function can return an iterable object so it does not matter if it is a function or a generator function. var … Read more
You have to bind your event handlers to correct context (this): onChange={this.setAuthorState.bind(this)}
You’re trying to export a default and declare a variable at the same time, which is invalid syntax. Consider the following, since we know that you can declare multiple variables using only one instance of the keyword, var a, b, c; the export definition wouldn’t make sense at all. export default var a, b, c; … Read more
2020 answer: there is still nothing built into the JS stdlib to handle de-denting long lines, although TC39 has discussed adding a new template literal that handles indentation. You have 2 options presently: The endent and dedent-js packages will handle this. Note the dedent-js package actually works with both tabs and spaces. var dedent = … Read more
Module creates a scope to avoid name collisions. Either expose your function to window object import {hello} from ‘./test.js’ window.hello = hello Or use addEventListener to bind handler. Demo <button type=”button” id=”hello”>Click Me</button> <script type=”module”> import {hello} from ‘./test.js’ document.querySelector(‘#hello’).addEventListener(‘click’, hello) </script>
The following for-of loop works: for (const e of a) The ES6 specification describes this as: ForDeclaration : LetOrConst ForBinding http://www.ecma-international.org/ecma-262/6.0/index.html#sec-for-in-and-for-of-statements-static-semantics-boundnames The imperative for loop will not work: for (const i = 0; i < a.length; i += 1) This is because the declaration is only evaluated once before the loop body is executed. http://www.ecma-international.org/ecma-262/6.0/index.html#sec-for-statement-runtime-semantics-labelledevaluation
Immediately, yes, by specification. From the MDN: The executor function is executed immediately by the Promise implementation, passing resolve and reject functions (the executor is called before the Promise constructor even returns the created object) This is defined in the ECMAScript specification (of course, it’s harder to read…) here (Step 9 as of this edit, showing … Read more
You can use object spread to have an optional property: let flag1 = true; let flag2 = false; // extra cases added by Abdull let optionalKey8 = 8; let optionalKey9 = undefined; let optionalKey10 = false; let optionalKey11 = null; let optionalKey12 = “twelve”; const obj = { requiredKey1: 1, requiredKey2: 2, …(flag1 && { … Read more
The correct syntax to destructure an array parameter is: function foo([a, b]) { console.log(`param1: ${a}, param2: ${b}`); } It can be called like this: foo([‘first’, ‘second’]); // Will output: // param1: first, param2: second According to Exploring ES6, section 11.6, you can use this to destructure parameters within arrow functions as well: const items = … Read more
You can still check component’s field members value change by KeyValueDiffers via DoCheck lifehook. import { DoCheck, KeyValueDiffers, KeyValueDiffer } from ‘@angular/core’; differ: KeyValueDiffer<string, any>; constructor(private differs: KeyValueDiffers) { this.differ = this.differs.find({}).create(); } ngDoCheck() { const change = this.differ.diff(this); if (change) { change.forEachChangedItem(item => { console.log(‘item changed’, item); }); } } see demo.