Try this: const eqSet = (xs, ys) => xs.size === ys.size && […xs].every((x) => ys.has(x)); const ws = new Set([1, 2, 3]); const xs = new Set([1, 3, 2]); const ys = new Set([1, 2, 4]); const zs = new Set([1, 2, 3, 4]); console.log(eqSet(ws, xs)); // true console.log(eqSet(ws, ys)); // false console.log(eqSet(ws, zs)); // … Read more
Here’s something slimmer, although it doesn’t avoid repeating the list of fields. It uses “parameter destructuring” to avoid the need for the v parameter. ({id, title}) => ({id, title}) (See a runnable example in this other answer). @EthanBrown’s solution is more general. Here is a more idiomatic version of it which uses Object.assign, and computed … Read more
It is destructuring, but contained within the parameters. The equivalent without the destructuring would be: const func = o => { var param1 = o.param1; var param2 = o.param2; //do stuff }
I’ve started employing the import * as obj style within my tests, which imports all exports from a module as properties of an object which can then be mocked. I find this to be a lot cleaner than using something like rewire or proxyquire or any similar technique. I’ve done this most often when needing … Read more
There is no way to do this with a single import statement, it does not allow for invocations. So you wouldn’t call it directly, but you can basically do just the same what commonjs does with default exports: // module.js export default function(options) { return { // actual module } } // main.js import m … Read more
While ugly and a bit repetitive, you can do ({x: oof.x, y: oof.y} = foo); which will read the two values of the foo object, and write them to their respective locations on the oof object. Personally I’d still rather read oof.x = foo.x; oof.y = foo.y; or [‘x’, ‘y’].forEach(prop => oof[prop] = foo[prop]); though.
You cannot rebind this in an arrow function. It will always be defined as the context in which it was defined. If you require this to be meaningful you should use a normal function. From the ECMAScript 2015 Spec: Any reference to arguments, super, this, or new.target within an ArrowFunction must resolve to a binding … Read more
You can use the spread operator on the keys of a freshly created array. […Array(n).keys()] or Array.from(Array(n).keys()) The Array.from() syntax is necessary if working with TypeScript
tl;dr: Use eslint-config-prettier, you can ignore the rest. ESLint contains many rules and those that are formatting-related might conflict with Prettier, such as arrow-parens, space-before-function-paren, etc. Hence using them together will cause some issues. The following tools have been created to use ESLint and Prettier together. prettier-eslint eslint-plugin-prettier eslint-config-prettier What it is A JavaScript module … Read more
You can use short circuit evaluation to supply a default if content is a falsy value, usually undefined or null in this case. const content = undefined const { item } = content || {} console.log(item) // undefined A less idiomatic (see this comment) way is to spread the content into an object before destructuring … Read more