setstate

问题 I want to add new key value to array ınto state? I tell you what I want to do below. How can I do that? 1. Start state in consruture method `this.state = { files: [] }' After I doing set state with active files this.setState({files: activeFiles}) Screen my state { files: [ { key1: val1, key2: val2, key3: val3 }, { key1: val1, key2: val2, key3: val3 }, { key1: val1, key2: val2, key3: val3 } ] } How to add new key value for each file? The state I want { files: [ { key1: val1, key2: val2, key3:

问题 I am very new to React-redux applications development and I am trying to understand how to dispatch another action as soon as the page loads. Following is my container code. I am using this (https://github.com/jpsierens/webpack-react-redux) boilerplate. let locationSearch; const ActivationPage = ({activateUser}) => { return ( <div className="container"> <h2>Activation Required</h2> <p>An Activation Email was sent to your email address. Please check your inbox to find the activation link</p> {

问题 I am using react's context API for storing USER_TOKEN for authentication purposes. Also I am maintaining a common fetch function in a separate module where I want to use this USER_TOKEN. And Its obvious that I cannot use this USER_TOKEN inside this module as it is not a react component. Is there any way I can use this USER_TOKEN inside this fetch function. I am storing USER_TOKEN into a context API variable after successful sign-in. Yes I know we could pass the variable from context whenever

问题 So I had a problem in my React application, I ran into a specific case where I needed to have multiple setState() calls in one method, and then have code run AFTER the states were set. The code below is a Dialog box used to add an account on the website. import React from 'react'; import Dialog from 'material-ui/Dialog'; import FlatButton from 'material-ui/FlatButton'; import TextField from 'material-ui/TextField'; /** * A modal dialog can only be closed by selecting one of the actions. */

问题 This question already has answers here : Why calling react setState method doesn't mutate the state immediately? (6 answers) Closed last year . I'm creating a very basic todo app. But I'm getting an issue with pushing todos into an array and assigning them to the state. constructor(props){ super(props); this.state = { todo : '', todos : [] }; }; todoValue(todo){ console.log(`Received the todo in the App : ${todo}`); this.setState({todo}); console.log(this.state.todo); } Here when I click a

问题 I'm trying to use lodash's find method to determine an index based on one attribute. In my case this is pet name. After that I need to change the adopted value to true using setState. The problem is however; I do not understand how to combine setState and _.find() As of right now I have this written. My main issue is figuring out how to finish this. adopt(petName) { this.setState(() => { let pet = _.find(this.state.pets, ['name', petName]); return { adopted: true }; }); } This does nothing at

问题 so I was programming an app with React and what happened is that I have a component with a fairly large list in its state. I am fetching a JSON file from network and then storing a filtered copy directly to component's state. Might be unoptimal solution BUT I think that's still okay and React should handle it I mean, it's just 10 kB. Anyway I decided to add a search input to my component and store its value to its state. Now I have both the large list and searchInput in its state which I am

问题 I am getting a flow error on a prop that I know is a string when I call this.setState() right before it. If I move the setState() call after the line that uses the prop, the error goes away. The error I'm getting is: null This type is incompatible with the expected param type of string undefined This type is incompatible with the expected param type of string Both errors occur on the same line of code. Here is a stripped down version of the component. See the implementation of

问题 Problem: Currently, I have a LoginForm component that has an "on-success" handler function handleOnSuccess . This the then linked to the parent component with an onTokenUpdate property defined by a "token-update" handler function handleUpdateToken . The problem is that the setState in the handleUpdateToken function is forcing an undesired rerender. Desired Outcome: What I ultimately need is to update the LoginForm component property token with the value obtained on success WITHOUT performing

问题 The React documentation says the following about setState: If you need to set the state based on the previous state, read about the updater argument below , Beside the following sentence, which I don't understand: If mutable objects are being used and conditional rendering logic cannot be implemented in shouldComponentUpdate() , calling setState() only when the new state differs from the previous state will avoid unnecessary re-renders. They say: The first argument is an updater function with