destructuring

问题 I have a function: export default ({ input: { name, onChange, value, ...restInput }, meta, ...rest }) => ( ... ); Given that 'name' is a string, 'onChange' is a function, 'value' is a string, 'meta' is an object, how can I add types to those parameters? My best guess would be like so: export default ({ input: { (name: String), (onChange: function), (value: String), ...restInput }, (meta: Object), ...rest }) => ( ... ); But it seems to have syntax errors. And even more I have no idea how to

问题 I have a function: export default ({ input: { name, onChange, value, ...restInput }, meta, ...rest }) => ( ... ); Given that 'name' is a string, 'onChange' is a function, 'value' is a string, 'meta' is an object, how can I add types to those parameters? My best guess would be like so: export default ({ input: { (name: String), (onChange: function), (value: String), ...restInput }, (meta: Object), ...rest }) => ( ... ); But it seems to have syntax errors. And even more I have no idea how to

问题 Lets say I have an object const obj = { width: 100, height: 200 } I wish to pass that object to a method myFunc( obj ); Inside that method I wish to pull out the height, but at the same time subtract a value. I only wish to do this once and after that it will never change. Doing the following will get me the correct height I want of say 150. let {height: localHeight} = obj; localHeight = localHeight - 50; How do I do the above in a single line ? Something like this - but I know this doesn't

问题 Lets say I have an object const obj = { width: 100, height: 200 } I wish to pass that object to a method myFunc( obj ); Inside that method I wish to pull out the height, but at the same time subtract a value. I only wish to do this once and after that it will never change. Doing the following will get me the correct height I want of say 150. let {height: localHeight} = obj; localHeight = localHeight - 50; How do I do the above in a single line ? Something like this - but I know this doesn't

问题 In ES6 we can do: let myFunc = ({name}) => { console.log(name) } myFunc({name:'fred'}) // => logs 'fred' But how do I do it for nested properties like this: myFunc({event:{target:{name:'fred'}}}) // => I want it to log 'fred' What should myFunc look like so that it logs 'fred'? I cannot change the object passed in. I wish to use destructuring to achieve this or some other suitable ES6 approach. 回答1: You can simply do like this: const myFunc = ({event: {target: {name}}}) => { console.log(name)

问题 I'm learning React and I have Eslint installed in my project. It started giving me errors like Use callback in setState when referencing the previous state. (react/no-access-state-in-setstate) Must use destructuring state assignment (react/destructuring-assignment) I tried to look this up but couldn't understand properly. Can someone point me in the right direction with this? Here is my code that throws the errors: class LoginForm extends React.Component { state = { data: { email: "",

问题 I have answered a few questions using destructing, I just want to take this one to the next level I want to not use reduce in this example but pure destructing if at all possible So the data's first row contains the attribute names of the object, How can I use that to be DRY i.e. I hoped for const obj = data.slice(1).map((titles) => ({ titles }) ) or similar So this works, but I miss one more step: const data = [ ["fruits","frozen","fresh","rotten"], ["apples",884,494,494], ["oranges",4848

问题 In javascript there is object destructuring so we can break down objects and just use the end key if the intermidiate objects are resused multiple times. e.g) const person = { firstName: "Bob", lastName: "Marley", city: "Space" } So instead of calling person.<> to get each value we can destructure it like this console.log(person.firstName) console.log(person.lastName) console.log(person.city) Destructured: const { firstName, lastName, city } = person; And call like this: console.log(firstName

问题 I have an object that contains symbols as keys. How do I do destructuring assignment in this case? let symbol = Symbol() let obj = {[symbol]: ''} let { /* how do I create a variable here, that holds the value of [symbol] property? */ } = obj I need to know if this possible, I do know the obvious and simple workarounds, but that's not what I am asking. UPD. Funny enough I knew how to do that but typescript produced errors, and I thought I did something wrong in JS. Here's a fix for typescript

问题 I have an object that contains symbols as keys. How do I do destructuring assignment in this case? let symbol = Symbol() let obj = {[symbol]: ''} let { /* how do I create a variable here, that holds the value of [symbol] property? */ } = obj I need to know if this possible, I do know the obvious and simple workarounds, but that's not what I am asking. UPD. Funny enough I knew how to do that but typescript produced errors, and I thought I did something wrong in JS. Here's a fix for typescript