Develop Reference

Can't read value from select tag in react JSX

delcare state object
const [addEmpData, setAddEmpData] = useState({
user_id:'',employee_id:'',name:'',date_of_join:'',gender:'',designation:'',user_role:''
})
here added value prop in select tag as addempData.gender.
and a onchange fn that set the value to state.
<div className="col-sm-6">
<div className="form-group">
<label className="col-form-label">Gender</label>
<select value={addEmpData.gender} onChange={(e)=>setAddEmpData({...addEmpData,gender:e.target.value})} className="select">
<option value='select'>Select</option>
<option value="Male">Male</option>
<option value='Female'>Female</option>
</select>
</div>
</div>

The proper implementation of controlled components in React base on your use case.
import { useState } from "react";
export default function App() {
const [addEmpData, setAddEmpData] = useState({
user_id: "",
employee_id: "",
name: "",
date_of_join: "",
gender: "",
designation: "",
user_role: ""
});
console.log(addEmpData);
return (
<div className="col-sm-6">
<div className="form-group">
<label className="col-form-label">Gender</label>
<select
value={addEmpData.gender}
onChange={(e) =>
setAddEmpData((prev) => ({ ...prev, gender: e.target.value }))
}
className="select"
>
<option value="select">Select</option>
<option value="Male">Male</option>
<option value="Female">Female</option>
</select>
</div>
</div>
);
}
You may also interact the demo in the CodeSandbox just click here

const [addEmpData, setAddEmpData] = useState({user_id:'',employee_id:'',name:'',date_of_join:'',gender:'',designation:'',user_role:''})
function handler(e)
{
const {name,value}=e.target;
setAddEmpData({
...addEmpData,
[name]:value
})
}
<div className="form-group">
<label className="col-form-label">Gender : </label>
<select value={addEmpData.gender} onChange={(e)=>handler(e)} name="gender" className="select">
<option value='select'>Select</option>
<option value="Male">Male</option>
<option value='Female'>Female</option>
</select>
</div>
You can try this code .
In this value will be read and changed in the state too
To try this code check this

The Problem
Using the current state in the setState is an anti-pattern in React.js.
The Solution
Use the prevState inside your setState to destructuring the unchanged properties:
onChange={
(e) => setAddEmpData((prevState) => {...prevState, gender:e.target.value})
}
Disclaimer
You can use any name instead of prevState but it must be the same on the left side and right side. prevState is just a paramere name but considered as a best practice to demonstrate the purpose of setState with the restructuring previous state.

Making first select <option> blank after mapping through array in JSX / React

render(){
let { classes } = this.props;
let list = classes.map((item, index) => {
return (
<option >{item}</option>
)
})
return(
<div className="filter-bar">
<form className="sort-form">
<div className="classSelect">
<span>select class</span>
<select name="classSelect" onChange={this.handleClassChange}}>
<option selected="selected" >Please choose class</option>
{list}
</select>
</div>
</form>
</div>
)
}
};
i want to map over an array and use each element as options in select dropdown, and also have an extra blank option which defaults until dropdown is clicked.
at the moment, the extra i have is available in the list, but default is always first element from array, whereas i want the default to be "Please choose your class"
can somebody explain?

render(){
const classes = [
'Lorem',
'Ipsum',
'dolor',
'Sit',
'ames'
]
let list = classes.map((item, index) => {
return (
<option >{item}</option>
)
})
return(
<div className="filter-bar">
<form className="sort-form">
<div className="classSelect">
<span>select class</span>
<select name="classSelect" onChange={this.handleClassChange.bind(this)}>
<option value="none" selected disabled hidden>
</option>
{list}
</select>
</div>
</form>
</div>
)
Like this?

Why is my URL [object%20Object] in API call?

My render is below. I have run out of ideas.
class Settings extends Component {
render(){
return(
<div className='App container'>
<h3>Select Currency</h3>
<select className="custom-select"
onChange={(prop, attr) => this.props.fetchData(id,value)}>
<option value='selected'></option>
<option value='EUR'>EUR</option
</select>
<Link to='/' className="btn" type="submit">Submit</Link>
</div>
)
}
}
}
Please help, what is wrong with my code? How can I solve this strange error?

Your onChange handler incorrect because no id and value is passed to it, only event object. From event.target object you should get this values, here is example, and short refactor of your component:
class Settings extends Component {
handleChange(e) {
this.props.fetchCurrency(e.target.id, e.target.value)
}
render(){
return(
<div className='App container'>
<h3>Select Currency</h3>
<select className="custom-select" id="inputGroup"
onChange={this.handleChange.bind(this)}>
<option value='selected'></option>
<option value='EUR'>EUR</option>
<option value='AUD'>AUD</option>
<option value='GBP'>GBP</option>
<option value='CAD'>CAD</option>
<option value='JPY'>JPY</option>
</select>
<Link to='/' className="btn btn-light btn-block" type="submit">Submit</Link>
</div>
)
}
}

onChange does by default callback with event (if you log id you'll see a Proxy object). So what you need to do is:
{(event) => this.props.fetchCurrency(event.target.value, event.target.options[event.target.options.selectedIndex].id)}
event.target.options[event.target.options.selectedIndex].id is needed if you want the selected option's ID - which for the time being seems absent in your code.

Element created in constructor not updated when component rerenders

Why is the <select> I create in the constructor not updated when I pick another flavor in it? The other select, as well as the text, is updated.
class ConstructorComponent extends React.Component {
constructor() {
super();
this.state = {
icecream: 'vanilla',
};
this.select = (
<select
value={this.state.icecream}
onChange={this.onChange}
>
<option value="chocolate">Chocolate</option>
<option value="vanilla">Vanilla</option>
<option value="strawberry">Strawberry</option>
</select>
);
}
onChange = event => {
this.setState({
icecream: event.target.value,
});
};
render() {
return (
<div>
Icecream flavor: {this.state.icecream}
<br />
{this.select}
<br />
<select
value={this.state.icecream}
onChange={this.onChange}
>
<option value="chocolate">Chocolate</option>
<option value="vanilla">Vanilla</option>
<option value="strawberry">Strawberry</option>
</select>
</div>
);
}
}
ReactDOM.render(
<ConstructorComponent />,
document.getElementById('container')
);
<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="container">
<!-- This element's contents will be replaced with your component. -->
</div>
I made it work by cloning this.select in render() like so: {React.cloneElement(this.select, {value: this.state.icecream})}
But making this.select a method instead, as suggested by several answers to my question is probably better. I'll see what works best with my actual code, and not just this dumbed down example :)

Because this.state.icecream in your first select is interpreted only once, when you define this.select in the constructor. So when your ConstructorComponent rerenders a second time when its state changes, there is nothing to update in your first select.
You need to define this.select as a function returning the <select>, like this:
this.select = () => {
return (
<select
value={this.state.icecream}
onChange={this.onChange}
>
<option value="chocolate">Chocolate</option>
<option value="vanilla">Vanilla</option>
<option value="strawberry">Strawberry</option>
</select>
)
}
And call this.select() in the render.
You can also create a reference to the <select> in the render by using the prop ref:
render() {
<select
value={this.state.icecream}
onChange={this.onChange}
ref={select => (this.select = select)} // the magic happens here
>
<option value="chocolate">Chocolate</option>
<option value="vanilla">Vanilla</option>
<option value="strawberry">Strawberry</option>
</select>
}
In doing so, you don't need to define this.select as a function in your constructor.

The first select doesn't work because it's only ever rendered once, in the constructor. The second select works because it's re-rendered every time the app state updates.
If it helps, don't think of JSX elements as "instances" of actual HTML elements. Think of them as a simple means of how you want your app to look in relation to your state. If my state is "a", then I render a select with "a", and if my state is "b", then I render a select with "b", and so on.

The first select box on the page is only rendered in the constructor which is called just once, thus the component will always remain the same as it does when it is first rendered. In other words it is static. The second select box is going to be re-rendered each time the component is updated.
In order to fix your code you can change your line in the constructor to a function:
this.select = () => (
<select
value={this.state.icecream}
onChange={this.onChange}
>
<option value="chocolate">Chocolate</option>
<option value="vanilla">Vanilla</option>
<option value="strawberry">Strawberry</option>
</select>
);
Then change your return statement to call this function:
<br />
{this.select()}
<br />

How to get selected value of a dropdown menu in ReactJS

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>`