destructuring

问题 I'd like to do something like this: const vegetableColors = {corn: 'yellow', peas: 'green'}; const {*} = vegetableColors; console.log(corn);// yellow console.log(peas);// green I can't seem to find or figure out how to do this but I really thought I had seen it done somewhere before! :P NOTE: I'm using Babel with stage set to 0 ; CONTEXT: I'm trying to be drier in JSX and not reference this.state or this.props everywhere. And also not have to keep adding properties to destructure if the data

问题 Not sure if this is a Mozilla-specific JS syntax, but I often found variables being declared this way, for example, in add-on SDK docs: var { Hotkey } = require("sdk/hotkeys"); and in various chrome Javascript ( let statement is being used in place of var ), let { classes: Cc, interfaces: Ci, results: Cr, utils: Cu } = Components; I found it very confusing but I am not being able to find any documentation about both syntax, even on MDN. 回答1: They're both JavaScript 1.7 features. The first one

问题 If I want to call a function like this: moo({ a: 4 }); Normally I'd have to phrase my function definition like this: function moo(myArgObj) { print(myArgObj.a); } But this awesome syntax is totally valid in spidermonkey for defining functions: function moo({ a, b, c }) { // valid syntax! print(a); // prints 4 } What is this feature? 回答1: It's called destructuring. You might find the most info at MDN: Destructuring assignment. The ECMAScript standards discussion can be found on their wiki page

问题 This question already has answers here : ES6 Array destructuring weirdness (4 answers) Closed 9 months ago . I am trying to do array destructuring in javascript and encounter some very puzzling behavior Here's the code I have -- let res = { start: {}, end: {}, }; [res.start.hour, res.start.minute] = [7, 20] [res.end.hour, res.end.minute] = [17, 30] console.log(res) The output is { start: { hour: 17, minute: 30 }, end: {} } For some reason, [17, 30] were assigned to res.start, instead of res

问题 This question already has answers here : Javascript object bracket notation ({ Navigation } =) on left side of assign (4 answers) Closed 2 years ago . How gonna assign in const { Types, Creators } in the below code I mean what Types gonna hold and what Creators gonna hold. const { Types, Creators } = createActions({ userRequest: ['username'], userSuccess: ['avatar'], userFailure: null }) var createActions = (function (config, options) { if (R.isNil(config)) { throw new Error('an object is

问题 Is there an elegant solution to destructure an object without specifying all the object's properties? I wondered if it was possible to use the spread operator but it seems like that's not possible because objects are not arrays! I guess it may be considered a bad idea to blindly declare variables but I think this would be useful for very large objects. 回答1: This is what the with(){} construction allowed: var obj = {a: 1}; with (obj) { console.log(a); } This construct is however severely

问题 open System let x = (1, 2) let (p, q) = x printfn "A %A" x printfn "B %A %A" p q let y = Some(1, 2) try let None = y () with | ex -> printfn "C %A" ex let Some(r, s) = y printfn "D %A" y // printfn "E %A %A" r s http://ideone.com/cS9bK0 When I uncomment the last line, the compiler rejects the code complaining /home/rRiy1O/prog.fs(16,19): error FS0039: The value or constructor 'r' is not defined /home/rRiy1O/prog.fs(16,21): error FS0039: The value or constructor 's' is not defined Is it not

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 3 years ago . Somewhat new to ES6 modules and find myself torn between the following 2 patterns... Pattern #1 - Destructuring on import import { func1, func2, func3 } from 'my-funcs'; Pattern #2 - Destructuring on const import * as myFuncs from 'my-funcs'; const { func1, func2, func3 } =

问题 I'm setting up a pattern that I've seen a few places for API authentication in Phoenix, using Comeonin and Guardian for JWT auth. When I POST to MyApp.SessionsController.create/2 from CURL, I get a user response back from MyApp.Session.authenticate/1 as I would expect. However, I'm supposed to destructure it into {:ok, jwt, _full_claims} , which can then be piped to Guardian. I use IO.inspect user to look at the user object and get the following error: Terminal: curl -H "Content-Type:

问题 I am trying to destructure object and assign it to new variable at the same time: let {x} = a = {x: 'cool'}; console.log(a, x); which outputs: //Object { x: "cool" } cool - in Firefox //ReferenceError: a is not defined - in Chrome, babel-node Why is there difference and what is the correct behavior? UPDATE: This is maybe more generic use case. While this works in all environments: var a = b = {x: 'cool'}; this statement is not working in chrome/babel-node: var {x} = a = {x: 'cool'}; /