Develop Reference

MaterialUI TextField lag issue. How to improve performance when the form has many inputs?

I encountered an annoying problem with Textfield using MateriaUI framework. I have a form with many inputs and it seems to be a bit laggy when typing or deleting values inside the fields. In other components when there are like 2 or 3 inputs there's no lag at all.
EDIT: The problem seems to be with my onChange handler.
Any help is much appreciated. Thanks in advance.
This is my custom input code:
import React, { useReducer, useEffect } from 'react';
import { validate } from '../utils/validators';
import TextField from '#material-ui/core/TextField';
import { ThemeProvider, makeStyles, createMuiTheme } from '#material-ui/core/styles';
import { green } from '#material-ui/core/colors';
const useStyles = makeStyles((theme) => ({
root: {
color: 'white'
},
input: {
margin: '10px',
'&& .MuiInput-underline:before': {
borderBottomColor: 'white'
},
},
label: {
color: 'white'
}
}));
const theme = createMuiTheme({
palette: {
primary: green,
},
});
const inputReducer = (state, action) => {
switch (action.type) {
case 'CHANGE':
return {
...state,
value: action.val,
isValid: validate(action.val, action.validators)
};
case 'TOUCH': {
return {
...state,
isTouched: true
}
}
default:
return state;
}
};
const Input = props => {
const [inputState, dispatch] = useReducer(inputReducer, {
value: props.initialValue || '',
isTouched: false,
isValid: props.initialValid || false
});
const { id, onInput } = props;
const { value, isValid } = inputState;
useEffect(() => {
onInput(id, value, isValid)
}, [id, value, isValid, onInput]);
const changeHandler = event => {
dispatch({
type: 'CHANGE',
val: event.target.value,
validators: props.validators
});
};
const touchHandler = () => {
dispatch({
type: 'TOUCH'
});
};
const classes = useStyles();
return (
<ThemeProvider theme={theme}>
<TextField
className={classes.input}
InputProps={{
className: classes.root
}}
InputLabelProps={{
className: classes.label
}}
id={props.id}
type={props.type}
label={props.label}
onChange={changeHandler}
onBlur={touchHandler}
value={inputState.value}
title={props.title}
error={!inputState.isValid && inputState.isTouched}
helperText={!inputState.isValid && inputState.isTouched && props.errorText}
/>
</ThemeProvider>
);
};
export default Input;

In addition to #jony89 's answer. You can try 1 more workaround as following.
On each keypress (onChange) update the local state.
On blur event call the parent's change handler
const Child = ({ parentInputValue, changeValue }) => {
const [localValue, setLocalValue] = React.useState(parentInputValue);
return <TextInputField
value={localValue}
onChange={(e) => setLocalValue(e.target.value)}
onBlur={() => changeValue(localValue)} />;
}
const Parent = () => {
const [valMap, setValMap] = React.useState({
child1: '',
child2: ''
});
return (<>
<Child parentInputValue={valMap.child1} changeValue={(val) => setValMap({...valMap, child1: val})}
<Child parentInputValue={valMap.child2} changeValue={(val) => setValMap({...valMap, child2: val})}
</>
);
}
This will solve your problems if you do not want to refactor the existing code.
But the actual fix would be splitting the state so that update in the state of child1 doesn't affect (change reference or mutate) state of child2.

Make sure to extract all constant values outside of the render scope.
For example, each render you are providing new object to InputLabelProps and InputProps which forces re-render of child components.
So every new object that is not must be created within the functional component, you should extract outside,
That includes :
const touchHandler = () => {
dispatch({
type: 'TOUCH'
});
};
const useStyles = makeStyles((theme) => ({
root: {
display: 'flex',
flexWrap: 'wrap',
color: 'white'
},
input: {
margin: '10px',
'&& .MuiInput-underline:before': {
borderBottomColor: 'white'
},
},
label: {
color: 'white'
}
}));
const theme = createMuiTheme({
palette: {
primary: green,
},
});
Also you can use react memo for function component optimization, seems fit to your case.

I managed to get rid of this lagging effect by replacing normal <TextField /> by <Controller /> from react-hook-form.
Old code with Typing Lag
<Grid item xs={12}>
<TextField
error={descriptionError.length > 0}
helperText={descriptionError}
id="outlined-textarea"
onChange={onDescriptionChange}
required
placeholder="Nice placeholder"
value={description}
rows={4}
fullWidth
multiline
/>
</Grid>
Updated Code with react-hook-form
import { FormProvider, useForm } from 'react-hook-form';
import { yupResolver } from '#hookform/resolvers/yup';
const methods = useForm({
resolver: yupResolver(validationSchema)
});
const { handleSubmit, errors, reset } = methods;
const onSubmit = async (entry) => {
console.log(`This is the value entered in TextField ${entry.name}`);
};
<form onSubmit={handleSubmit(onSubmit)}>
<Grid item xs={12}>
<FormProvider fullWidth {...methods}>
<DescriptionFormInput
fullWidth
name="name"
placeholder="Nice placeholder here"
size={matchesXS ? 'small' : 'medium'}
bug={errors}
/>
</FormProvider>
</Grid>
<Button
type="submit"
variant="contained"
className={classes.btnSecondary}
startIcon={<LayersTwoToneIcon />}
color="secondary"
size={'small'}
sx={{ mt: 0.5 }}
>
ADD
</Button>
</form>
import React from 'react';
import PropTypes from 'prop-types';
import { Controller, useFormContext } from 'react-hook-form';
import { FormHelperText, Grid, TextField } from '#material-ui/core';
const DescriptionFormInput = ({ bug, label, name, required, ...others }) => {
const { control } = useFormContext();
let isError = false;
let errorMessage = '';
if (bug && Object.prototype.hasOwnProperty.call(bug, name)) {
isError = true;
errorMessage = bug[name].message;
}
return (
<>
<Controller
as={TextField}
name={name}
control={control}
defaultValue=""
label={label}
fullWidth
InputLabelProps={{
className: required ? 'required-label' : '',
required: required || false
}}
error={isError}
{...others}
/>
{errorMessage && (
<Grid item xs={12}>
<FormHelperText error>{errorMessage}</FormHelperText>
</Grid>
)}
</>
);
};
With this use of react-hook-form I could get the TextField more responsive than earlier.

Dynamic content with React js Modal

I want to get dynamic content with React js modal I am using package react-responsive-modal. First I render all the post through map. Now I want when I click the individual post the modal should pop up and show me only that particular post's title and body. Now I can't figure out how to get an individual post in modal.
Is it possible to do that via third-party package or I have to make custom modal for that?
import React from 'react';
import Modal from 'react-responsive-modal';
import Axios from 'axios';
const styles = {
fontFamily: 'sans-serif',
textAlign: 'center'
};
class App extends React.Component {
state = {
posts: [],
open: false
};
componentDidMount() {
let url = 'https://jsonplaceholder.typicode.com/posts';
Axios.get(url).then(res => {
this.setState({
posts: res.data.slice(0, 10)
});
console.log(res.data.slice(0, 10));
});
}
onOpenModal = () => {
this.setState({ open: true });
};
onCloseModal = () => {
this.setState({ open: false });
};
renderPosts() {
return this.state.posts.map(post => {
return (
<div
key={post.id}
style={{ width: 400, height: 400, backgroundColor: 'orange' }}
onClick={this.onOpenModal}
>
<h1>{post.title}</h1>
</div>
);
});
}
renderModal(id, title, body) {
return this.state.posts.map(post => {
return (
<div key={post.id} style={{ width: 400, height: 400, backgroundColor: 'orange' }}>
<h1>{post.id}</h1>
<h1>{post.title}</h1>
<p>{post.body}</p>
</div>
);
});
}
render() {
const { open } = this.state;
return (
<div style={styles}>
<h2>react-responsive-modal</h2>
<div>{this.renderPosts()}</div>
<Modal open={open} onClose={this.onCloseModal} center>
<h2>Simple centered modal</h2>
<div>{this.renderModal()}</div>
</Modal>
</div>
);
}
}
export default App;

You'll need to introduce some additional state on your App component that keeps track of the currently selected post. In your onOpenModal() method, you can update that state with the index of the post that was clicked. Then, in renderModal(), you can check what the selected post is and only render that post instead of mapping over the entire array.
class App extends React.Component {
state = {
posts: [],
open: false,
selectedPost: null // Keep track of the selected post
};
componentDidMount() {
let url = "https://jsonplaceholder.typicode.com/posts";
Axios.get(url).then(res => {
this.setState({
posts: res.data.slice(0, 10)
});
console.log(res.data.slice(0, 10));
});
}
onOpenModal = i => {
this.setState({
open: true,
selectedPost: i // When a post is clicked, mark it as selected
});
};
onCloseModal = () => {
this.setState({ open: false });
};
renderPosts = () => {
return this.state.posts.map((post, i) => {
return (
<div
key={post.id}
style={{ width: 400, height: 400, backgroundColor: "orange" }}
onClick={() => this.onOpenModal(i)} // Pass the id of the clicked post
>
<h1>{post.title}</h1>
</div>
);
});
}
renderModal = () => {
// Check to see if there's a selected post. If so, render it.
if (this.state.selectedPost !== null) {
const post = this.state.posts[this.state.selectedPost];
return (
<div
style={{ width: 400, height: 400, backgroundColor: "orange" }}
>
<h1>{post.id}</h1>
<h1>{post.title}</h1>
<p>{post.body}</p>
</div>
);
}
}
render() {
const { open } = this.state;
return (
<div style={styles}>
<h2>react-responsive-modal</h2>
<div>{this.renderPosts()}</div>
<Modal open={open} onClose={this.onCloseModal} center>
<h2>Simple centered modal</h2>
<div>{this.renderModal()}</div>
</Modal>
</div>
);
}
}

In the post onClick function set the post id/index in state along with the open flag
Inside the modal render use the saved index/id to pass that post to the modal as a param/prop.
You dont need to map over all posts inside the modal.
Sample
onOpenModal = (index) => {
this.setState({ open: true, selectedPostIndex: index });
};
onCloseModal = () => {
this.setState({ open: false, selectedPostIndex: undefined })
}
renderPosts() {
return this.state.posts.map((post, index) => {
return (
<div key={post.id} onClick={() => this.onOpenModal(index)}>
<h1>{post.title}</h1>
</div>
)
})
}
render() {
....
<Modal open={open} onClose={this.onCloseModal} center>
<h2>Simple centered modal</h2>
<div>{this.renderModal(this.state.posts[this.state.selectedPostIndex])}</div>
</Modal>
....
}
renderModal(post) {
return (
<div key={post.id} style={{ width: 400, height: 400, backgroundColor: 'orange' }}>
<h1>{post.id}</h1>
<h1>{post.title}</h1>
<p>{post.body}</p>
</div>
)
}

Using React Hooks
Create a modal with dynamic props like this
export default function Modal({
open,
setOpen,
onConfirm,
title,
description,
confirmText,
})
Then render the component.
i did it like this
const getModal = () => {
return (
<Modal open={open} setOpen={setOpen} title={title} description={description} confirmText={confirmText} onConfirm={confirmAction} />
)
}
and then when you want to display your dynamic modal
use a function like this
ConfirmAction can not be a function you should call the function inside that Modal according to that confirmation
const createModal = (title, description, confirmText, confirmAction) => {
setTitle(title);
setDescription(description);
setConfirmText(confirmText);
setConfirmAction(confirmAction);
setOpen(true);
}

Initialize your state with one array which will hold
state = {
posts: [],
open: false,
modalShow: [false,false,false,false,false,false,false,false,false,false] // this is 10 as you have only 10 posts
};
Now modify render posts
onOpenModal = (id) => {
const newModalShow = [...this.state.modalShow];
newModalShow[id] = true;
this.setState({ modalShow: newModalShow});
};
renderPosts() {
return this.state.posts.map((post,index) => {
return (
<Fragement>
<div
key={post.id}
style={{ width: 400, height: 400, backgroundColor: 'orange' }}
onClick={()=>this.onOpenModal(index)}
>
<h1>{post.title}</h1>
</div>
<Modal open={this.state.modalShow[index]} onClose={this.onCloseModal} center>
<h2>post.title</h2>
<div>{this.renderModal()}</div>
</Modal>
<Fragement>
);
});
}

inputs in component aren't updating correctly

I have component that is going to be used many times. It's basically to inputs that will represent two width and height dimensions.
Couple of things going on with them right now. When I start typing in them, when they are both empty, the last character is not recorded. if I type:
1234 x 1234
when I refresh the inputs show:
1234 x 123
then if I edit one of the inputs, the other will just go blank.
Here's my code:
import React from 'react';
// Shared Components
import { FlexRow } from 'components/shared/Flexbox';
import { TextInput } from 'components/shared/TextInput';
export class RenderDimensionsInput extends React.Component {
state = {
readOnly: '',
width: null,
height: null
};
handleChange = e => {
console.log('e.target.name', e.target.name);
this.setState({ [e.target.name]: e.target.value });
console.log('this.state.height', this.state.height);
console.log('this.state.width', this.state.width);
this.props.onChange(this.state.height, this.state.width);
};
render() {
return (
<div>
<FlexRow>
<TextInput
label={this.props.label}
style={{ width: '135px', marginRight: '10px' }}
defaultValue={this.props.values.width}
name="width"
// onChange={this.props.onChange}
onChange={e => this.handleChange(e)}
/>
<span>x</span>
<TextInput
style={{ width: '135px', marginLeft: '10px' }}
defaultValue={this.props.values.height}
name="height"
// onChange={this.props.onChange}
onChange={e => this.handleChange(e)}
/>
</FlexRow>
</div>
);
}
}
export class TextInput extends React.Component {
state = {
readOnly: '',
};
render() {
return (
<FlexColumn
style={{
alignItems: 'baseline',
paddingBottom: s[3],
}}>
<Input
{...this.props}
type={this.props.type || 'text'}
defaultValue={this.props.defaultValue}
onChange={this.props.onChange}
readOnly={this.state.readOnly}
/>
<Label>{this.props.label}</Label>
</FlexColumn>
);
}
}

You are using the value from state directly after setting the state, but setState is async which means that there is no guarantee that at that moment you are using the latest state in: this.props.onChange(this.state.height, this.state.width);
So it is better to use it that way:
this.setState({ [e.target.name]: e.target.value }, () => {
this.props.onChange(this.state.height, this.state.width);
});

Add value of checkbox to an array when it is clicked

I have this situation where I want to transfer userid to an array which is defined in State.
I want to do it when I click on the checkbox to select it, and I want to remove the userid from the array when I deselect the checkbox
import React, { Component } from "react";
import {
View,
Text,
StyleSheet,
FlatList,
AsyncStorage
} from "react-native";
import axios from 'axios';
import { Button, Container, Content, Header, Body, Left, Right, Title } from 'native-base';
import Icon from 'react-native-vector-icons/Ionicons';
import { List, ListItem, SearchBar, CheckBox } from "react-native-elements";
// const itemId = this.props.navigation.getParam('itemId', 'NO-ID');
// const otherParam = this.props.navigation.getParam('otherParam', 'some default value');
class TeacherSubjectSingle extends Component{
static navigationOptions = {
header : null
}
// static navigationOptions = {
// headerStyle: {
// backgroundColor: '#8E44AD',
// },
// headerTintColor: '#fff',
// }
state = {
class_id: null,
userid: null,
usertype: null,
student_list: [],
faq : [],
checked: [],
}
componentWillMount = async () => {
const {class_id, student_list, userid, usertype} = this.props.navigation.state.params;
await this.setState({
class_id : class_id,
student_list : student_list,
userid : userid,
usertype : usertype,
})
console.log(this.state.class_id)
var result = student_list.filter(function( obj ) {
return obj.class_section_name == class_id;
});
this.setState({
student_list: result[0]
})
}
renderSeparator = () => {
return (
<View
style={{
height: 1,
width: "100%",
backgroundColor: "#CED0CE",
}}
/>
);
};
checkItem = (item) => {
const { checked } = this.state;
console.log(item)
if (!checked.includes(item)) {
this.setState({ checked: [...checked, item] });
} else {
this.setState({ checked: checked.filter(a => a !== item) });
}
console.log(checked)
};
render(){
return (
<Container>
<Header style={{ backgroundColor: "#8E44AD" }}>
<Left>
<Button transparent onPress={()=> this.props.navigation.navigate('ClassTeacher')}>
<Icon name="ios-arrow-dropleft" size={24} color='white' />
</Button>
</Left>
<Body>
<Title style={{ color: "white" }}>{this.state.class_id}</Title>
</Body>
<Right>
{this.state.checked.length !== 0 ? <Button transparent onPress={()=> this.props.navigation.navigate('ClassTeacher')}>
<Text>Start Chat</Text>
</Button> : null}
</Right>
</Header>
<View style={{flex: 1, backgroundColor: '#fff'}}>
<List containerStyle={{ borderTopWidth: 0, borderBottomWidth: 0 }}>
<FlatList
data={this.state.student_list.students}
extraData={this.state.checked}
renderItem={({ item }) => (
<ListItem
// roundAvatar
title={<CheckBox
title={item.name}
checkedColor='#8E44AD'
onPress={() => this.checkItem(item.userid)}
checked={this.state.checked.includes(item.userid)}
/>}
// subtitle={item.email}
// avatar={{ uri: item.picture.thumbnail }}
//containerStyle={{ borderBottomWidth: 0 }}
onPress={()=>this.props.navigation.navigate('IndividualChat', {
rc_id: item.userid,
userid: this.state.userid,
usertype: this.state.usertype,
subject_name: this.state.student_list.subject_name
})}
/>
)}
keyExtractor={item => item.userid}
ItemSeparatorComponent={this.renderSeparator}
/>
</List>
</View>
</Container>
);
}
}
export default TeacherSubjectSingle;
const styles = StyleSheet.create({
container:{
flex:1,
alignItems:'center',
justifyContent:'center'
}
});
this is the code for the same, I have created a function checkItem()for the same and it is working, the only problem is, when I click on the first item, it will output the blank array, I select the second item and it will return the array with first item and so on. Please help me resolve it, thanks in advance

Its because you are printing this.state.checked value just after the setState, setState is async, it will not immediately update the state value.
You can use setState callback method to check the updated state values.
Write it like this:
checkItem = (item) => {
const { checked } = this.state;
let newArr = [];
if (!checked.includes(item)) {
newArr = [...checked, item];
} else {
newArr = checked.filter(a => a !== item);
}
this.setState({ checked: newArr }, () => console.log('updated state', newArr))
};
Check this answer for more details about setState:
Why calling setState method doesn't mutate the state immediately?

Try below code:
checkItem = (e) => {
let alreadyOn = this.state.checked; //If already there in state
if (e.target.checked) {
alreadyOn.push(e.target.name); //push the checked value
} else {
//will remove if already checked
_.remove(alreadyOn, obj => {
return obj == e.target.name;
});
}
console.log(alreadyOn)
this.setState({checked: alreadyOn});
}

Like this, with an event listener and the .push method of an array.
var checkboxes = document.querySelectorAll('input[type=checkbox]');
var myArray = [];
for (var i = 0; i < checkboxes.length; i++) {
checkboxes[i].addEventListener("click", function(e) {
myArray.push(e.target.value);
console.log(myArray);
});
};
<div>
<input type="checkbox" name="feature" value="scales" />
<label >Scales</label>
</div>
<div>
<input type="checkbox" name="feature" value="horns" />
<label >Horns</label>
</div>
<div>
<input type="checkbox" name="feature" value="claws" />
<label >Claws</label>
</div>

React Native Elements Checkbox Should be checked after clicking

I'm using React Native Elements CheckBox inside List Items, of Flat List.
import React, { Component } from "react";
import { View, Text, StyleSheet, FlatList } from "react-native";
import axios from "axios";
import {
Button,
Container,
Content,
Header,
Body,
Left,
Right,
Title
} from "native-base";
import Icon from "react-native-vector-icons/Ionicons";
import { List, ListItem, SearchBar, CheckBox } from "react-native-elements";
// const itemId = this.props.navigation.getParam('itemId', 'NO-ID');
// const otherParam = this.props.navigation.getParam('otherParam', 'some default value');
class TeacherSubjectSingle extends Component {
static navigationOptions = {
header: null
};
// static navigationOptions = {
// headerStyle: {
// backgroundColor: '#8E44AD',
// },
// headerTintColor: '#fff',
// }
state = {
class_id: null,
userid: null,
usertype: null,
student_list: [],
faq: [],
checked: []
};
componentWillMount = async () => {
const {
class_id,
student_list,
userid,
usertype
} = this.props.navigation.state.params;
await this.setState({
class_id: class_id,
student_list: student_list,
userid: userid,
usertype: usertype
});
console.log(this.state.class_id);
var result = student_list.filter(function(obj) {
return obj.class_section_name == class_id;
});
this.setState({
student_list: result[0]
});
};
renderSeparator = () => {
return (
<View
style={{
height: 1,
width: "100%",
backgroundColor: "#CED0CE"
}}
/>
);
};
checkItem = item => {
const { checked } = this.state;
if (!checked.includes(item)) {
this.setState({ checked: [...checked, item] });
} else {
this.setState({ checked: checked.filter(a => a !== item) });
}
};
render() {
return (
<Container>
<Header style={{ backgroundColor: "#8E44AD" }}>
<Left>
<Button
transparent
onPress={() => this.props.navigation.navigate("ClassTeacher")}
>
<Icon name="ios-arrow-dropleft" size={24} color="white" />
</Button>
</Left>
<Body>
<Title style={{ color: "white" }}>{this.state.class_id}</Title>
</Body>
<Right />
</Header>
<View style={{ flex: 1, backgroundColor: "#fff" }}>
<List containerStyle={{ borderTopWidth: 0, borderBottomWidth: 0 }}>
<FlatList
data={this.state.student_list.students}
renderItem={({ item }) => (
<ListItem
// roundAvatar
title={
<CheckBox
title={item.name}
onPress={() => this.checkItem(item.userid)}
checked={this.state.checked.includes(item.userid)}
/>
}
// subtitle={item.email}
// avatar={{ uri: item.picture.thumbnail }}
containerStyle={{ borderBottomWidth: 0 }}
onPress={() =>
this.props.navigation.navigate("IndividualChat", {
rc_id: item.userid,
userid: this.state.userid,
usertype: this.state.usertype,
subject_name: this.state.student_list.subject_name
})
}
/>
)}
keyExtractor={item => item.userid}
ItemSeparatorComponent={this.renderSeparator}
/>
</List>
</View>
</Container>
);
}
}
export default TeacherSubjectSingle;
const styles = StyleSheet.create({
container: {
flex: 1,
alignItems: "center",
justifyContent: "center"
}
});
Above is my code for the same, I have tried every possibility and checked the GitHub page for the same, but my items are not getting checked if I press on the checkbox.
My renderItem will have an array to render which is having a field like 'name' and 'userid'.
This is the example of the code from where I have coppied the coding for the same, where it is working
I want to save selected ids to an array so that I can pass that as a prop to the next screen.

Since FlatList is a PureComponent, it will not re-render the items unless the data changes. If you want the FlatList to re-render when checked array changes, you need to pass it to e.g. extraData.
<FlatList
data={this.state.student_list.students}
extraData={this.state.checked}
renderItem={({ item }) => {
// ...
}}
keyExtractor={item => item.userid}
ItemSeparatorComponent={this.renderSeparator}
/>