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React JS Routing on 2 Option Values

I am new to React and I'm having a hard time figuring out how to return (or route to) a new page based off of two user selected options? I am trying to load a unique set of buttons for the user to select from depending on the options that they select. When reselecting different options the page would reload with the appropriate buttons.
import React from 'react';
import "./App.css";
import "./styles.css"
import Header from './components/Header/Header';
import Footer from './components/Footer/Footer';
import ObservationText from './components/ObservationText/ObservationText';
import { Dropdown } from 'bootstrap';
/*
let activity = document.getElementById('Activity-Type');
let role = document.getElementById('Role-Type');
activity.addEventListener('change', () => update());
role.addEventListener('change', () => update());
function update(){
const roleValue = document.getElementById('Role-Type').value;
const activityValue = document.getElementById('Activity-Type').value;
//console.log(activityValue + roleValue);
switch (activityValue + roleValue){
case 'ND_A18_FP1VO1-CREW' :
ND_A18_FP1VO1CREW();
break;
default:
//consle.log('this is the default message');
break;
}
}
function ND_A18_FP1VO1CREW(){
alert('ND A18 FP1 + VO1-CREW Selected');
}
*/
function getActivity(el){
const option = el.value;
if(option ==='esc')return
console.log(option)
return option;
}
function getRole(el){
const option = el.value;
if(option ==='esc')return
console.log(option)
return option;
}
function App(){
return (
<div className="App">
<Header/>
<h1>
<label htmlFor ="Activity-Type" className ="sideBySideField">Activity
<select id="Activity-Type" onChange={e => getActivity(e.target)}>
<option value="" disabled="" defaultValue=""> Select... </option>
<option value="ND A18 FP1">ND_A18_FP1</option>
<option value="ND A18 FP2">ND_A18_FP2</option>
<option value="ND BPLANE">ND_BPLANE</option>
<option value="NM A18 FP2">NM_A18_FP2</option>
<option value="AK A18 FP3">AK_A18_FP3</option>
</select>
</label>
<label htmlFor="Role" className ="sideBySideField">Role
<select id="Role-Type" onChange={e => getRole(e.target)}>
<option value="" disabled="" defaultValue=""> Select... </option>
<option value="Other General">Other-General</option>
<option value="VO1 CREW">VO1CREW</option>
<option value="VO2-CREW">VO2CREW</option>
<option value="VO3-CREW">VO3CREW</option>
<option value="VO4-CREW">VO4CREW</option>
<option value="EO2-EO Observer">EO2EO_Observer</option>
<option value="EO1-EO Observer">EO1EO_Observer</option>
<option value="Observer 1-GCS Observer">Observer1GCS_Observer</option>
<option value="FTD-Flight Test Director">FTDFlight_Test_Director</option>
</select>
</label>
</h1>
<div class="center">
<ObservationText/>
</div>
<Footer/>
</div>
);
}
export default App;

Bind Id through another property React [duplicate]

I'm using react and I want to get the value of the selected option of a dropdown in react but I don't know how. Any suggestions? thanks!
My dropdown is just a select like:
<select id = "dropdown">
<option value="N/A">N/A</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>

The code in the render method represents the component at any given time.
If you do something like this, the user won't be able to make selections using the form control:
<select value="Radish">
<option value="Orange">Orange</option>
<option value="Radish">Radish</option>
<option value="Cherry">Cherry</option>
</select>
So there are two solutions for working with forms controls:
Controlled Components Use component state to reflect the user's selections. This provides the most control, since any changes you make to state will be reflected in the component's rendering:
example:
var FruitSelector = React.createClass({
getInitialState:function(){
return {selectValue:'Radish'};
},
handleChange:function(e){
this.setState({selectValue:e.target.value});
},
render: function() {
var message='You selected '+this.state.selectValue;
return (
<div>
<select
value={this.state.selectValue}
onChange={this.handleChange}
>
<option value="Orange">Orange</option>
<option value="Radish">Radish</option>
<option value="Cherry">Cherry</option>
</select>
<p>{message}</p>
</div>
);
}
});
React.render(<FruitSelector name="World" />, document.body);
JSFiddle: http://jsfiddle.net/xe5ypghv/
Uncontrolled Components The other option is to not control the value and simply respond to onChange events. In this case you can use the defaultValue prop to set an initial value.
<div>
<select defaultValue={this.state.selectValue}
onChange={this.handleChange}
>
<option value="Orange">Orange</option>
<option value="Radish">Radish</option>
<option value="Cherry">Cherry</option>
</select>
<p>{message}</p>
</div>
http://jsfiddle.net/kb3gN/10396/
The docs for this are great: http://facebook.github.io/react/docs/forms.html
and also show how to work with multiple selections.
UPDATE
A variant of Option 1 (using a controlled component) is to use Redux and React-Redux to create a container component. This involves connect and a mapStateToProps function, which is easier than it sounds but probably overkill if you're just starting out.

Implement your Dropdown as
<select id = "dropdown" ref = {(input)=> this.menu = input}>
<option value="N/A">N/A</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>
Now, to obtain the selected option value of the dropdown menu just use:
let res = this.menu.value;

It should be like:
import React, { useState } from "react";
export default function App() {
const getInitialState = () => {
const value = "Orange";
return value;
};
const [value, setValue] = useState(getInitialState);
const handleChange = (e) => {
setValue(e.target.value);
};
return (
<div>
<select value={value} onChange={handleChange}>
<option value="Orange">Orange</option>
<option value="Radish">Radish</option>
<option value="Cherry">Cherry</option>
</select>
<p>{`You selected ${value}`}</p>
</div>
);
}
you can see it here: https://codesandbox.io/s/quizzical-https-t1ovo?file=/src/App.js:0-572

Just use onChange event of the <select> object.
Selected value is in e.target.value then.
By the way, it's a bad practice to use id="...". It's better to use ref=">.."
http://facebook.github.io/react/docs/more-about-refs.html

As for front-end developer many time we are dealing with the forms in which we have to handle the dropdowns and we have to
use the value of selected dropdown to perform some action or the send the value on the Server, it's very simple
you have to write the simple dropdown in HTML just put the one onChange method for the selection in the dropdown
whenever user change the value of dropdown set that value to state so you can easily access it in AvFeaturedPlayList
1
remember you will always get the result as option value and not the dropdown text which is displayed on the screen
import React, { Component } from "react";
import { Server } from "net";
class InlineStyle extends Component {
constructor(props) {
super(props);
this.state = {
selectValue: ""
};
this.handleDropdownChange = this.handleDropdownChange.bind(this);
}
handleDropdownChange(e) {
this.setState({ selectValue: e.target.value });
}
render() {
return (
<div>
<div>
<div>
<select id="dropdown" onChange={this.handleDropdownChange}>
<option value="N/A">N/A</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>
</div>
<div>Selected value is : {this.state.selectValue}</div>
</div>
</div>
);
}
}
export default InlineStyle;

Using React Functional Components:
const [option,setOption] = useState()
function handleChange(event){
setOption(event.target.value)
}
<select name='option' onChange={handleChange}>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>

import React from 'react';
import Select from 'react-select';
const options = [
{ value: 'chocolate', label: 'Chocolate' },
{ value: 'strawberry', label: 'Strawberry' },
{ value: 'vanilla', label: 'Vanilla' },
];
class App extends React.Component {
state = {
selectedOption: null,
};
handleChange = selectedOption => {
this.setState({ selectedOption });
console.log(`Option selected:`, selectedOption);
};
render() {
const { selectedOption } = this.state;
return (
<Select
value={selectedOption}
onChange={this.handleChange}
options={options}
/>
);
}
}
And you can check it out on this site.

It is as simple as that. You just need to use "value" attributes instead of "defaultValue" or you can keep both if a pre-selected feature is there.
....
const [currentValue, setCurrentValue] = useState(2);
<select id = "dropdown" value={currentValue} defaultValue={currentValue}>
<option value="N/A">N/A</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>
.....
setTimeut(()=> {
setCurrentValue(4);
}, 4000);
In this case, after 4 secs the dropdown will be auto-selected with option 4.

I was making a drop-down menu for a language selector - but I needed the dropdown menu to display the current language upon page load. I would either be getting my initial language from a URL param example.com?user_language=fr, or detecting it from the user’s browser settings. Then when the user interacted with the dropdown, the selected language would be updated and the language selector dropdown would display the currently selected language.
In the spirit of the other answers using food examples, I got all sorts of fruit goodness for you.
First up, answering the initially asked question with a basic React functional component - two examples with and without props, then how to import the component elsewhere.
Next up, the same example - but juiced up with Typescript.
Then a bonus finale - A language selector dropdown component using Typescript.
Basic React (16.13.1) Functional Component Example. Two examples of FruitSelectDropdown , one without props & one with accepting props fruitDetector
import React, { useState } from 'react'
export const FruitSelectDropdown = () => {
const [currentFruit, setCurrentFruit] = useState('oranges')
const changeFruit = (newFruit) => {
setCurrentFruit(newFruit)
}
return (
<form>
<select
onChange={(event) => changeFruit(event.target.value)}
value={currentFruit}
>
<option value="apples">Red Apples</option>
<option value="oranges">Outrageous Oranges</option>
<option value="tomatoes">Technically a Fruit Tomatoes</option>
<option value="bananas">Bodacious Bananas</option>
</select>
</form>
)
}
Or you can have FruitSelectDropdown accept props, maybe you have a function that outputs a string, you can pass it through using the fruitDetector prop
import React, { useState } from 'react'
export const FruitSelectDropdown = ({ fruitDetector }) => {
const [currentFruit, setCurrentFruit] = useState(fruitDetector)
const changeFruit = (newFruit) => {
setCurrentFruit(newFruit)
}
return (
<form>
<select
onChange={(event) => changeFruit(event.target.value)}
value={currentFruit}
>
<option value="apples">Red Apples</option>
<option value="oranges">Outrageous Oranges</option>
<option value="tomatoes">Technically a Fruit Tomatoes</option>
<option value="bananas">Bodacious Bananas</option>
</select>
</form>
)
}
Then import the FruitSelectDropdown elsewhere in your app
import React from 'react'
import { FruitSelectDropdown } from '../path/to/FruitSelectDropdown'
const App = () => {
return (
<div className="page-container">
<h1 className="header">A webpage about fruit</h1>
<div className="section-container">
<h2>Pick your favorite fruit</h2>
<FruitSelectDropdown fruitDetector='bananas' />
</div>
</div>
)
}
export default App
FruitSelectDropdown with Typescript
import React, { FC, useState } from 'react'
type FruitProps = {
fruitDetector: string;
}
export const FruitSelectDropdown: FC<FruitProps> = ({ fruitDetector }) => {
const [currentFruit, setCurrentFruit] = useState(fruitDetector)
const changeFruit = (newFruit: string): void => {
setCurrentFruit(newFruit)
}
return (
<form>
<select
onChange={(event) => changeFruit(event.target.value)}
value={currentFruit}
>
<option value="apples">Red Apples</option>
<option value="oranges">Outrageous Oranges</option>
<option value="tomatoes">Technically a Fruit Tomatoes</option>
<option value="bananas">Bodacious Bananas</option>
</select>
</form>
)
}
Then import the FruitSelectDropdown elsewhere in your app
import React, { FC } from 'react'
import { FruitSelectDropdown } from '../path/to/FruitSelectDropdown'
const App: FC = () => {
return (
<div className="page-container">
<h1 className="header">A webpage about fruit</h1>
<div className="section-container">
<h2>Pick your favorite fruit</h2>
<FruitSelectDropdown fruitDetector='bananas' />
</div>
</div>
)
}
export default App
Bonus Round: Translation Dropdown with selected current value:
import React, { FC, useState } from 'react'
import { useTranslation } from 'react-i18next'
export const LanguageSelectDropdown: FC = () => {
const { i18n } = useTranslation()
const i18nLanguage = i18n.language
const [currentI18nLanguage, setCurrentI18nLanguage] = useState(i18nLanguage)
const changeLanguage = (language: string): void => {
i18n.changeLanguage(language)
setCurrentI18nLanguage(language)
}
return (
<form>
<select
onChange={(event) => changeLanguage(event.target.value)}
value={currentI18nLanguage}
>
<option value="en">English</option>
<option value="de">Deutsch</option>
<option value="es">Español</option>
<option value="fr">Français</option>
</select>
</form>
)
}
An invaluable resource for React/Typescript

You can handle it all within the same function as following
<select className="form-control mb-3" onChange={(e) => this.setState({productPrice: e.target.value})}>
<option value="5">5 dollars</option>
<option value="10">10 dollars</option>
</select>
as you can see when the user select one option it will set a state and get the value of the selected event without furder coding require!

If you want to get value from a mapped select input then you can refer to this example:
class App extends React.Component {
constructor(props) {
super(props);
this.state = {
fruit: "banana",
};
this.handleChange = this.handleChange.bind(this);
}
handleChange(e) {
console.log("Fruit Selected!!");
this.setState({ fruit: e.target.value });
}
render() {
return (
<div id="App">
<div className="select-container">
<select value={this.state.fruit} onChange={this.handleChange}>
{options.map((option) => (
<option value={option.value}>{option.label}</option>
))}
</select>
</div>
</div>
);
}
}
export default App;

import {React, useState }from "react";
function DropDown() {
const [dropValue, setDropValue ]= useState();
return <>
<div>
<div class="dropdown">
<button class="btn btn-secondary" type="button" id="dropdownMenuButton1" data-bs-toggle="dropdown" aria-expanded="false">
{dropValue==null || dropValue=='' ?'Select Id':dropValue}
</button>
<ul class="dropdown-menu" aria-labelledby="dropdownMenuButton1">
<li><a class="dropdown-item" onClick={()=> setDropValue('Action')} href="#">Action</a></li>
<li><a class="dropdown-item" onClick={()=> setDropValue('Another action')} href="#">Another action</a></li>
<li><a class="dropdown-item" onClick={()=> setDropValue('Something else here')} href="#">Something else here</a></li>
</ul>
</div>
</div>
</>
}
export default DropDown

<select value ={this.state.value} onChange={this.handleDropdownChange}>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
</select>

As mentioned by Karen above you can just use the target value from the event triggered. Here is a small snippet of the code
`<select class="form-select py-2"
onChange={(e) => setVotersPerPage(e.target.value)}>
<option value="10">10</option>
<option value="25">25</option>
<option value="50">50</option>
</select>`

How to get the value of a dropdown menu in ReactJS

I'm trying to get the value of a dropdown menu that looks like this:
<ul className="tabs" data-component={true}>
<li>
<section className="sort-list" data-component={true}>
<select value={0} className="sort" data-element={true}>
<option key="0" value="0">Any Topic</option>
<option key="1" value="1">Art</option>
<option key="2" value="2">Auto</option>
//...and so on
I've seen similar questions, but trying to alert(sort).value won't work (along with some other variants) so I think I need to string together my selectors?
I can use either the value or the text, as the goal is to keep the filter applied even when a user goes back to the previous page.
How do I get the key, value, or text of the options?

You need to add onchage event to your select.
change = (event) => {
this.setState({
topic: event.target.value
})
}
<select onChange={this.change} value={0} className="sort" data-element={true}
<option key="0" value="0">Any Topic</option>
<option key="1" value="1">Art</option>
<option key="2" value="3">Auto</option>
</select>
DEMO
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.0/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.0/umd/react-dom.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/6.21.1/babel.min.js"></script>
<div id="root"></div>
<script type="text/babel">
class App extends React.Component {
constructor() {
super();
this.state = {
topic: ''
};
}
change = (event) => {
this.setState({
topic: event.target.value
})
}
render() {
return (
<div>
<p>
Selected topic: {this.state.topic}
</p>
<select onChange={this.change} className="sort" data-element={true}>
<option key="0" value="0">Any Topic</option>
<option key="1" value="1">Art</option>
<option key="2" value="2">Auto</option>
</select>
</div>
);
}
}
ReactDOM.render(
<App />,
document.getElementById('root')
);
</script>

The Reactjs way would be to have a select box component which has an onChange handler. Something like this:
class MySelect extends React.Component {
onChange = (val) => {
// save the val somewhere..
this.setState({currentVal: val})
}
render() {
return <select onChange={this.onChange}> { getOptions() } </select>
}
}

Add onChange property to element.
Here is a simple code snippet for a working example.
import React, { useState } from 'react';
import { oneOfType, string, number } from 'prop-types';
function MyDropdown({ selected: preSelected }) {
const [selected, setSelected] = useState(preSelected);
const onChange = evt => {
setSelected(evt.target.value);
}
return (
<div>
<select onChange={onChange} value={selected}>
<option value={1}>Opption 1</option>
<option value={2}>Opption 2</option>
<option value={3}>Opption 3</option>
</select>
{selected && <div>Selcted: {selected}</div>}
</div>
)
}
MyDropdown.propTypes = {
selected: oneOfType([string, number])
};
MyDropdown.defaultProps =
selected: 1
};
You can also check it live on CodeSandbox: https://codesandbox.io/s/react-codesandbox-2voc6

React - How to Populate two Dropdowns based on selection in another

I need to change the contents of dropdown Method&Minorhead based on the selection in dropdown MajorHead using React.
If I select cheating in majorhead, then it's supposed to show a&b in minorHead and apple, orange in Method.
If I select abduction in majorhead, then it's supposed to show AB&BC in minorhead and cat, dog in Method...
import React, { Component } from 'react';
class Profile extends Component {
render() {
return (
<form>
<div className="form-group">
<label for="inputState">Major head</label>
<select id="inputState" className="form-control"/>
<option selected>Choose...</option>
<option>Cheating</option>
<option>Abduction</option>
<option>House brake</option>
</div>
<div className="form-group">
<label for="inputState">Minor head</label>
<select id="inputState" className="form-control"/>
<option selected>Choose...</option>
<option>a</option>
<option>b</option>
<option>AB</option>
<option>BC</option>
<option>X</option>
<option>Y</option>
</div>
<div className="form-group">
<label for="inputState">method</label>
<select id="inputState" className="form-control"/>
<option selected>Choose...</option>
<option>apple</option>
<option>orange</option>
<option>cat</option>
<option>dog</option>
</div>
</form>
)
}
}
export default Profile;

For each option in your major head Select, i would create an array of supported values for method and minor.
class App extends React.Component {
constructor(props) {
super(props)
this.state = {
selectedView: 'Cheating'
}
}
render() {
const { selectedView } = this.state
const VIEWS = [
{
name: 'Cheating',
minor: ['a', 'b'],
method: ['apple', 'orange']
}, {
name: 'Abductions',
minor: ['AB', 'BC', 'X'],
method: ['cat', 'dog']
}
]
const getMajorMethod = () => {
const view = VIEWS.filter(({name}) => name === selectedView)[0]
return (
<div>
<select>
{view.minor.map(m => <option>{m}</option>)}
</select>
<select>
{view.method.map(m => <option>{m}</option>)}
</select>
</div>
)
}
return (
<div>
<select onChange={(e) => this.setState({selectedView: e.target.value})}>
{VIEWS.map(({name}) => <option value={name}>{name}</option>)}
</select>
{getMajorMethod()}
</div>
)
}
}
ReactDOM.render(<App />, document.getElementById('app'))
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<div id="app"></div>
A structure like this will allow you to (within your initial MAJOR select) map over your VIEWS and apply the name prop to the options.
You can then have another map that shows two other selects (minor & method) with the VIEWS relative minor and method arrays being their options

Problems navigating to another component(and page) on click using 'this.props.router.push'

I want to navigate to another page when an image is clicked in a separate component. Using this.props.router.push should work to achieve this. However I get this error when the image is clicked Uncaught TypeError: Cannot read property 'props' of null. This is the component I have the image that has the on click function :
import React, { Component } from 'react';
import { connect } from 'react-redux';
import { addCart } from '../../actions';
import { withRouter } from 'react-router';
import ProductPage from '
import Shirt from './camodye.jpeg';
import Tape from './Tape.png';
import RegularHat from './regularhat.jpg';
export class WebShop extends Component {
constructor(props){
super(props);
this.state = {value: 'medium', cartData: {} };
this.handleClick = this.handleClick.bind(this);
this.change = this.change.bind(this);
}
handleClick() {
let cart = {price:0,item:"userselection",size:this.state.value};
this.props.onCartAdd(cart);
}
change(e){
this.setState({value: e.target.value})
}
itemSelection(){
let userOrder = {price:0,item:"",size:""};
let userItem = "";
if (userItem == "shirt1") {
let itemPrice = 20.00;
}
}
goProductPage() {
this.props.router.push({ProductPage});
}
render() {
console.log('aa');
return (
<div className='Webshop' id='Webshop'>
<ul id="Productlist">
<div className='Product'>
<img src={Shirt} onClick={this.goProductPage}></img>
<button onClick={this.handleClick} className="addit">Add to cart</button>
<select id="size" onChange={this.change} value={this.state.value}>
<option value="medium">Medium</option>
<option value="large">Large</option>
<option value="x-large">X-large</option>
</select>
</div>
<div className='Product'>
<img src={RegularHat}></img>
<button onClick={this.handleClick} className="addit">Add to cart</button>
<select id="size" onChange={this.change} value={this.state.value}>
<option value="medium">Medium</option>
<option value="large">Large</option>
<option value="x-large">X-large</option>
</select>
</div>
<div className='Product'>
<img src={Tape}></img>
<button onClick={this.handleClick} className="addit">Add to cart</button>
<select id="size" onChange={this.change} value={this.state.value}>
<option value="medium">Medium</option>
<option value="large">Large</option>
<option value="x-large">X-large</option>
</select>
</div>
</ul>
</div>
);
}
}
This is my productpage.js that has the ProductPage component:
import React, { Component } from 'react';
export default class ProductPage extends Component {
render() {
return (
<div className= "ProductPage" id="ProductPage">
</div>
);
}
}
Why I'm I getting this error? Is this the best way to do what I want?

You need to bind this to your goProductPage method in constructor:
constructor(props){
super(props);
this.goProductPage = this.goProductPage.bind(this);
}