Replace element at specific position in an array without mutating it
You can use Object.assign: Object.assign([], array, {2: newItem});
ecmascript-6
Destructuring array get second value?
You can skip parametr name just by putting comma var num = [1, 2, 3, 4, 5]; var [ ,x] = num; for more: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment#Ignoring_some_returned_values section Ignoring some returned values
A module cannot have multiple default exports
Quick Way As sometimes you can just reopen a file as stated in other answers, it doesn’t always help, however. When you see lags like this one (and other weirdness from TS service), you can restart the TypeScript service using the following way: See more details on TypeScript tool window help center page. Previous functionality … Read more
destructuring falsy and null with default parameters
Only undefined will cause the default initialiser to run in destructuring and function parameter targets. If you want to fall back to your default for all falsy values, use the good old || operator instead: const email = person.email || ”; Or target a mutable variable and use logical OR assignment afterwards: let { email … Read more
Calling a method from another method in the same class
You need to use the this keyword instead of self. runMyTest() { this.myTest(); } A side note If you are nesting standard functions notation then this is not lexically bound (will be undefined). To get around this, use Arrow Functions (preferred), .bind, or locally define this outside of the function. class Test { constructor() { … Read more
Using await within a Promise
You do this: async function outerFunction() { const value = await somethingAsynchronous(); if (value === something) { return ‘It Worked!’; } throw Error(‘Nope. Try again.’); } Using async wraps the result of outerFunction with a Promise. If you want that wrapping promise to resolve to something, just return it from the async function. If you … Read more
ES6 Iterate over class methods
You can use Object.getOwnPropertyNames on the prototype: Object.getOwnPropertyNames( Animal.prototype ) // [ ‘constructor’, ‘getAnimalType’ ]
Export const arrow function or basic function?
The differences are minuscule. Both declare a variable. A const variable is constant also within your module, while a function declaration theoretically could be overwritten from inside the module An arrow function is a function expression, not a function declaration, and the assignment can lead to problems for circular dependencies An arrow function cannot be … Read more
ES6 modules in local files – The server responded with a non-JavaScript MIME type
A simple fix for me that wasn’t listed here was this: I had an import statement bringing an object from a different file, which I did via this line: import { Cell } from ‘./modules/Cell’; What broke the code and caused the MIME type error was not having .js appended to the end of ./modules/Cell. … Read more
Is there any reasons to use axios instead ES6 fetch [closed]
A few reasons for using Axios over Fetch: Ability to monitor request progress This is more of a question between XMLHttpRequest (which powers axios) or Fetch API. Fetch API currently does not provide any way to get notified of the request progress, a feature which powers feedback mechanism for large file uploads for example. Axios, … Read more