Develop Reference

Importing New React Component Compiles But Does Not Render

So I've been having problems with this code that i am working on
Dependencies: React, Redux, Eslinter, PropTypes, BreadCrumb
There's a view page that imports various components from other files
The Existing Structure Goes:
import Component from './Component.js';
...
let var = '';
...
if (this.state.value !=== null) {
var = <Component/>
}
...
render() {
return(
<div>
SomeContent
{var}
</ div>
)
}
When i try to import my created PureComponent the code Compiles.
Component Dependencies: { Button, Modal }React-Bootstrap, React, PropTypes
However the page does not render, and i cant figure out the reason why it would not render when it is introduced in the same manner as the existing structure Above
Update: I have tried making a bare minimum component returning just a simple Div & got the same result
RESOLVED:
There was a depreciated reference in my component to Modal from 'react-bootstrap' which still contained the node_module reference title but not the corresponding JS file which they have since moved to 'react-modal'

import Component from './Component.js';
let entity = '';
if (this.state.value !== null) {
entity = <Component />
}
render() {
return (
<div>
SomeContent
{entity}
</ div>
)
}
Firstly, You can not use var keyword for naming a variable and also, please check your condition fulfillment.

When dealing with state and conditional rendering, you should put conditions within the render method (or in a class field):
Working example:
import React from "react";
import OtherComponent from "../OtherComponent";
class Example extends React.Component {
constructor() {
super();
this.state = {
value: ""
};
this.handleChange = this.handleChange.bind(this);
}
handleChange(event) {
this.setState({ value: event.target.value });
}
render() {
return (
<div>
SomeContent
{this.state.value && <OtherComponent />}
<br />
<input
value={this.state.value}
placeholder="Type something..."
onChange={this.handleChange}
/>
</div>
);
}
}
export default Example;

How to get label values dynamically and adding the numbers together from different input with reactjs

Created a Div and inside it I have label element and input element, I want to get different label values in each div. How to re-use my div component
instead of coding the same code again.
I have tried to search in Stackoverflow plus googles, Haven't received a better answer.
Here I have created div element with just label and input element and then I have rendured this component in App.js file:
How can I reuse the same code/component to create 2 more div and having different labels values in it? Ho can I add numbers together from different input ( which I am getting from different components input)
Appreciate all your help!
import React, { Component } from 'react';
import './calculator.css';
class Boxes extends Component {
state = {
inputOne: '',
inputtwo: '',
inputthree: ''
}
getInputValue = (e) => {
const value = e.target.value;
console.log('value: ', value);
this.setState({
inputOne: Number(e.target.value)
});
}
render() {
const { value } = this.props // destructuring
const {inputOne, inputtwo, inputthree } = this.state
return (
<div className="boxes">
<label className="boxeslevel" htmlFor="text">
{value}
</label>
<input
name="text"
type="text"
onChange={this.getInputValue}
/>
</div>
);
}
}
export default Boxes;
import React, { Component } from 'react';
import './App.css';
import Boxes from './components/calculator';
class App extends Component {
render(){
return (
<div className="wrapper">
<Boxes value= {"Value 1:"} onChange={this.props.onChange}/>
<Boxes value= {"Value 2:"} onChange={this.props.onChange}/>
<Boxes value= {"Value 3:"} onChange={this.props.onChange}/>
<ShowResult />
</div>
);
}
}
export default App;

You should pass a prop to your componente to be reuse. As you notice you are using local component state in your component, like const {value} = this.state try the same approach but with props like const {value} = this.props and then passing that prop in the component usage like
<Boxes value={“label 1”}/>
<Boxes value={“label 2”}/>
That would work. Hope it help you
Remember you can use as many props you need and access them as the same way mention above

You can do something like this:
class Boxes extends Component {
render() {
const { value } = this.props // value coming from props
return (
<div className="wrapper">
<div className="firstBox">
<label htmlFor="text">
{value}
</label>
<input name="text" type="text" />
</div>
</div >
);
}
}
export default Boxes;
and in your app component something like this:
import React, { Component } from 'react';
import './App.css';
import Boxes from './components/calculator';
class App extends Component {
render(){
return (
<div className="App">
<Boxes value={1}/>
<Boxes value={2}/>
<Boxes value={3}/>
</div>
);
}
}
export default App;
Here is live demo link

You have to use props instead of state in your Boxes component. Then you can pass the required props from the App component.
App.js
import React, { Component } from 'react';
import './App.css';
import Boxes from './components/calculator';
class App extends Component {
render(){
return (
<div className="App">
<Boxes value={"Value 1"}/>
<Boxes value={"Value 2"}/>
<Boxes value={"Value 3"}/>
</div>
);
}
}
export default App;
Boxes.js
import React, { Component } from 'react';
import './calculator.css';
class Boxes extends Component {
render() {
const { value } = this.props // destructuring
return (
<div className="wrapper">
<div className="firstBox">
<label htmlFor="text">
{value}
</label>
<input name="text" type="text" />
</div>
</div >
);
}
}
export default Boxes;

How to deal with this.setState issue in react JS

for some reason the value of my setState is not updating when I press the next button. It is for a progress bar where the progress bar adds 20 each time the button is pressed. So like value:this.state.value+20 Does anyone know whats going on? Any help is appreciated. Thanks!
import React, {Component} from "react";
import { Button, Progress } from 'reactstrap';
import "../src/Questions.css"
class Questions extends React.Component {
handleClick=()=>{
alert(this.state.value);
this.setState({
value:this.state.value +20
})
}
render() {
this.state = {
value:10
}
return(
<div>
<div><Progress value={this.state.value} /></div>
<div className="howMuchText">How much does it cost to build an app</div>
<div className="nextButton">
<Button onClick={this.handleClick} color="primary" size="lg">Next</Button>
</div>
</div>
)
}
}
export default Questions;

The reason this is not updating is because you are updating the state using setState in your handleClick function then reseting it in your render function so you are undoing your update. Try this.
Change your source from what you have to this:
import React, { Component } from "react";
import { Button, Progress } from 'reactstrap';
import "../src/Questions.css"
//you've imported component so you don't need to do React.Component
class Questions extends Component {
state = {
value: 10,
}
handleClick = () =>{
alert(this.state.value);
this.setState({
value: this.state.value +20
})
}
render() {
return(
<div>
<div><Progress value={this.state.value} /></div>
<div className="howMuchText">How much does it cost to build an app</div>
<div className="nextButton">
<Button onClick={this.handleClick} color="primary" size="lg">Next</Button>
</div>
</div>
)
}
}
This should do it. Hope this helps.

changing state inside the render function is wrong. At every update, state is going to change. State is immutable at react. You can initialize it inside your constructor function.
constructor(props) {
super(props);
this.state = {
value:10
}
}

You should use constructor to initialize the value. What are you doing wrong in your code when you click button it is updating the value but setState re-render the so it again to initialize value=10.
import React, {Component} from "react";
import { Button, Progress } from 'reactstrap';
import "../src/Questions.css"
class Questions extends React.Component {
constructor(props) {
super(props);
this.state = { value:10
}
}
handleClick=()=>{
alert(this.state.value);
this.setState({
value:this.state.value +20
})
}
render() {
return(
<div>
<div><Progress value={this.state.value} /></div>
<div className="howMuchText">How much does it cost to build an app</div>
<div className="nextButton">
<Button onClick={this.handleClick} color="primary" size="lg">Next</Button>
</div>
</div>
)
}
}
export default Questions;

How can I update the Youtube video using my search function?

I am trying to pass a search query from an input in searchBar.js to app.js and then back into its child Video in order to search for a video and play it.
I am not sure what I'm doing wrong, as the video is not updating.
Do I need to rerender the video component or something like that?
I am using the react-youtube module for react integration with the YoutubeAPI.
https://github.com/kdelalic/Shuffle
app.js (parent) class:
import React, { Component } from 'react';
import "../css/app.css";
import Video from "./video";
import TopBar from "./topBar";
export default class App extends Component {
constructor(props) {
super(props);
this.state = {
searchQuery: null
};
}
myCallback(dataFromChild) {
this.setState({ searchQuery: dataFromChild });
}
render() {
return (
<div>
<TopBar parentCallBack={this.myCallback}/>
<Video query={this.state.searchQuery} />
</div>
);
}
}
topBar.js class:
import React, { Component } from 'react';
import {Navbar} from 'react-materialize';
import '../css/topBar.css';
import SearchBar from './searchBar'
export default class TopBar extends Component {
myCallback(dataFromChild) {
this.props.parentCallBack(dataFromChild);
}
render() {
return (
<div className="wrapper">
<Navbar className="logo" brand='Shuffle+' right>
<SearchBar callBack={this.myCallback}/>
</Navbar>
</div>
);
}
}
searchBar.js class:
import React, { Component } from 'react';
import {NavItem, Icon} from 'react-materialize';
import '../css/searchBar.css';
export default class SearchBar extends Component {
constructor(props) {
super(props);
this.state = {value: ''};
this.handleChange = this.handleChange.bind(this);
this.handleSubmit = this.handleSubmit.bind(this);
}
handleChange(event) {
this.setState({value: event.target.value});
}
handleSubmit(event) {
this.props.callBack(this.state.value);
event.preventDefault();
}
render() {
return (
<div className="wrapper">
<form className="form" onSubmit={this.handleSubmit}>
<label>
<input className="input" type="text" value={this.state.value} onChange={this.handleChange} />
</label>
</form>
<NavItem className="searchButton">
<Icon>search</Icon>
</NavItem>
</div>
);
}
}

This looks relatively ok with one exception.
myCallback(dataFromChild) {
this.props.parentCallBack(dataFromChild);
}
// ...when being used
<SearchBar callBack={this.myCallback}/>
The problem is, when the callBack function is called from the Child, the this of the function is set to the child component.
You have a couple options here when passing a function into a child as a callback.
Bind in property
<SearchBar callBack={this.myCallback.bind(this)}/>
The downside is that the function is copied every time the render function is called.
Bind in constructor
As you've already done, you can bind the this context of the function to the parent in the constructor.
class TopBar extends Component {
constructor() {
// ...
this.myCallback = this.myCallback.bind(this);
}
}
Downside is that it's terse and you have to write this for every function you need to bind to the component.
ES Class Property Arrow Functions
This is my personal favorite. The downside is that you need babel and the stage 2 proposal to transpile your code.
class TopBar extends Component {
myCallback = () => {
// ...
}
render() {
<SearchBar callback={this.myCallback} />
}
}

How to make/access state using props in react?

I made an app with multiple components and want their state to be accessed using parent/main app, I'm not sure how to get it. what i'm trying to do is when i change state in main "App" the component state should change. One of the component is 'checkbox' and now i want to access its state using parent app, I made multiple attempts but not getting it done. my code goes like this..
This is Main 'App' code:
import React, { Component } from 'react';
import Checkbox from './checkbox';
import Radio from './Radio';
import ToggleSwitch from './ToggleSwitch';
import PrimaryButton from './PrimaryButton';
class App extends Component {
onClick(isClicked){
isChecked:true
};
render() {
return (
<div id="form">
<Checkbox
onClick={this.onClick}
/>
<RadioButton
onClick={this.onClick}
/>
</div>
);
}
}
export default App;
The component i want to access goes like this:
import React, { Component } from 'react';
class Checkbox extends Component {
constructor(props){
super(props);
this.state={
isChecked:true
};
};
onCheck(){
this.setState({
isChecked: !this.state.isChecked
});
this.props.isClicked()
};
render() {
return (
<div>
<div
className={this.state.isChecked ? 'checked': 'unchecked'}
onClick={this.onCheck.bind(this)}
>
</div>
</div>
);
}
}
export default Checkbox;

You forgot to bind the onClick event in the app component, try this it will work :
class App extends Component {
onClick(isClicked){
console.log('isClicked', isClicked);
};
render() {
return (
<div id="form">
<Checkbox onClick={this.onClick.bind(this)}/>
</div>
);
}
}

If you already have onClick handler for the Checkbox I don't see why you couldn't just move the state up to the App component and just pass down a callback from there to the Checkbox that will update the parent state. That seems like a more React way to do it, to me.
class App extends Component {
constructor(props){
super(props);
this.state={
isChecked:true
}
}
onClick = (isClicked) => {
this.setState({isChecked: !this.state.isChecked})
}
render() {
return (
<div id="form">
<Checkbox
onClick={this.onClick}
ischecked={this.state.isChecked}
/>
</div>
);
}
}
Component
class Checkbox extends Component {
onCheck(){
this.props.onClick()
}
render() {
return (
<div>
<div
className={this.props.isChecked ? 'checked': 'unchecked'}
onClick={this.onCheck.bind(this)}
>
</div>
</div>
)
}
}