es6-promise

问题 So, I'm simply trying to set state in my react app. Simply get data from Axios, and then set state. But no matter what I do, the state will not set. I've tried putting it in a callback since it's async and putting it my component did mount and component did update alas nothing. any pointers? class App extends Component { componentDidUpdate() {} constructor(props) { super(props); this.state = { Catogories: [ "Business", "Entertainment", "General", "Health", "Science", "Sports", "Technology" ],

问题 I have created this live-search component: class SearchEngine extends Component { constructor (props) { super(props); this.handleChange = this.handleChange.bind(this); this.handleSearch = this.handleSearch.bind(this); } handleChange (e) { this.props.handleInput(e.target.value); //Redux } handleSearch (input, token) { this.props.handleSearch(input, token) //Redux }; componentWillUpdate(nextProps) { if(this.props.input !== nextProps.input){ this.handleSearch(nextProps.input, this.props

问题 I have created this live-search component: class SearchEngine extends Component { constructor (props) { super(props); this.handleChange = this.handleChange.bind(this); this.handleSearch = this.handleSearch.bind(this); } handleChange (e) { this.props.handleInput(e.target.value); //Redux } handleSearch (input, token) { this.props.handleSearch(input, token) //Redux }; componentWillUpdate(nextProps) { if(this.props.input !== nextProps.input){ this.handleSearch(nextProps.input, this.props

问题 I am wanting to create an alert inside my function which tracks if any other instances of the same function have fired during a 15 second period. this is what I have so far: bar = 0; async function Counting() { bar += 1; foo = bar; new Promise(resolve => setTimeout(resolve, 5000)); if (bar == foo) { //Do something } else { return; } } I'm using bar as a global counter and foo as a function instance counter, but for some reason all instances of the function update at the same time. How can I

问题 I am wanting to create an alert inside my function which tracks if any other instances of the same function have fired during a 15 second period. this is what I have so far: bar = 0; async function Counting() { bar += 1; foo = bar; new Promise(resolve => setTimeout(resolve, 5000)); if (bar == foo) { //Do something } else { return; } } I'm using bar as a global counter and foo as a function instance counter, but for some reason all instances of the function update at the same time. How can I

问题 I am using the async/await function the following way async function(){ let output = await string.replace(regex, async (match)=>{ let data = await someFunction(match) console.log(data); //gives correct data return data }) return output; } But the returned data is an promise object. Just confused about the way it should be implemented in such functions with callback. 回答1: An easy function to use and understand for some async replace : async function replaceAsync(str, regex, asyncFn) { const

问题 I have been reading up on methods to implement a polling function and found a great article on https://davidwalsh.name/javascript-polling. Now using a setTimeout rather than setInterval to poll makes a log of sense, especially with an API that I have no control over and has shown to have varying response times. So I tried to implement such a solution in my own code in order to challenge my understanding of callbacks, promises and the event loop. I have followed guidance outlined in the post

问题 I need to have an "endless" while-loop which has promises inside it. Here's some example code: let noErrorsOccured = true while (noErrorsOccured){ someAsyncFunction().then(() => { doSomething(); }).catch((error) => { console.log("Error: " + error); noErrorsOccured = false; }); } function someAsyncFunction() { return new Promise ((resolve, reject) => { setTimeout(() => { const exampleBool = doSomeCheckup(); if (exampleBool){ resolve(); } else { reject("Checkup failed"); } }, 3000); }); } So

问题 I have written about a half a dozen functions in nodejs using promises, i want really post all of that code, instead i will post a simulated example , so i can encapsulate my problem succinctly. so say i have 2 functions below: foo = () => { return new Promise( ( r , rj ) => { setTimeout( () => { r('DONE'); }, 3000 ); }); } And bar = () => { return new Promise( (r , rj) => { r('ALL DONE !') } ) } Now i would like to avoid the callback hell and do the following: foo().then( (resp) => console

问题 I'm using async/await with React Native. My result from response.json() is: { _45: 0, _81: 0, _65: null, _54: null } For whatever reason, the actual response I want is located in _65 and I have no idea what these random keys are. It seems that it is related to the fact that .json() returns a Promise. componentDidMount() { this.getData().then(data => this.setState({ data })) } async getData() { try { let response = await fetch(myUrl) let json = await response.json() return json } catch(err) {