React + Redux - Input onChange is very slow when typing in when the input have a value from the state
JavascriptReactjsReduxJavascript Problem Overview
I got my input who is filled by a value from my state.
<input id="flashVars" name="flashVars" type="text" value={settings.flashVarsValue} disabled={isDisabled} onChange={handleChange} />
Settings
is my state with Redux. When i put a value into my input, i must specify a onChange
function. This is my onChange function:
handleFlashVarsChange(e) {
let { dispatch } = this.props;
dispatch( changeFlashVarsValue(e.target.value) );
}
It change the state value flashVarsValue
for the value of the input. But when i type in my input, it lags. I don't understand why i should call the dispatch each time i change the input value.
Is there any way who can give less lags?
My reducer:
import { ACTIONS } from '../utils/consts';
const initialState = {
...
flashVarsValue: '',
...
};
export function formSettings(state = initialState, action = '') {
switch (action.type) {
...
case ACTIONS.CHANGE_FLASHVARS_VALUE:
return Object.assign({}, state, {
flashVarsValue: action.data
});
default:
return state;
}
}
My action:
export function changeFlashVarsValue(data) {
return {
type: ACTIONS.CHANGE_FLASHVARS_VALUE,
data: data
}
}
Thank you
Javascript Solutions
Solution 1 - Javascript
I had a similar problem when I was editing a grid with a million rows, so what I did was to change the update logic, in your case handleChange
to be called only on the event onBlur
instead of onChange
. This will only trigger the update when you lose focus. But don't know if this would be a satisfactory solution for you.
Solution 2 - Javascript
The answer for me was to use the shouldComponentUpdate lifecycle hook. This has already been given as an answer in a comment by Mike Boutin (about a year ago :) ), but an example might help the next visitor here.
I had a similar problem, with the text input being lost, and slow and jumpy. I was using setState to update the formData in my onChange event.
I found that the form was doing a complete re-render with every keypress, as the state had changed. So to stop this, I overrode the function:
shouldComponentUpdate(nextProps, nextState) {
return this.state.formErrors !== nextState.formErrors);
}
I show an error notification panel on form submission with any new or changed validation errors, and that's the only time I need to re-render.
If you have no child components, you could probably just set the form component's shouldComponentUpdate to always return false.
Solution 3 - Javascript
I know this is an old question, but if you want to fire onChange on a text input, you probably want to debounce your event. This thread does a good job breaking it down, but I think this would work for the op's example:
import debounce from 'debounce'
function debounceEventHandler(...args) {
const debounced = debounce(...args)
return function (e) {
e.persist();
return debounced(e);
}
}
const Container = React.createClass({
handleFlashVarsChange(e) {
let { dispatch } = this.props;
//basic redux stuff
this.props.changeFlashVarsValue(e.target.value));
},
render() {
const handleChange = debounceEventHandler(this.handleFlashVarsChange, 15);
return (
<input id="flashVars" onChange={handleChange} />
)
}
}
//...prep and return your redux container
Solution 4 - Javascript
The issue here is possibly re-renders. You're passing in "settings" (your entire state) to your component containing the "input", and we don't know how the rest of your connected components are coupled to state. Check to see if as a result of the state object mutating, you're rerendering much more than just the input on every keystroke. The solution to this is to more directly pass in the specific parts of state you need from mapStateToProps (in this case, maybe only pass in "flashVarsValue" if that's all this component needs, and make sure other components aren't also passed the whole state) and use PureRenderMixin or Dan Abramov's https://github.com/gaearon/react-pure-render if you're using ES6 components to not re-render if your props haven't changed
Solution 5 - Javascript
The answer is not to re-render your component on every key stroke, only if user stops typing in. Something like this:
shouldComponentUpdate(nextProps, nextState) {
if (!textInputReRender)
return false;
else
return true;
}
onTextInputChange = (propName, propValue) => {
if (inputChangeTimerId)
clearTimeout(inputChangeTimerId);
inputChangeTimerId = setTimeout(() => {
inputChangeTimerId = null;
const newState = {};
textInputReRender = true;
newState[propName] = propValue;
this.setState(newState);
}, 500);
textInputReRender = false;
}
Solution 6 - Javascript
Use onChangeText
instead
import { TextInput, View} from "react-native";
import { connect } from "react-redux";
import React, { Component, useState } from "react";
function SearchTextInput(props) {
const { keyword = "", setKeyword } = props;
return (
<TextInput
style={styles.searchInputText}
placeholder={"placeholder here"}
value={keyword}
onChangeText={setKeyword(t)}
/>
);
}
const mapStateToProps = state => {
return {
keyword: state.search.keyword,
search: state.search
};
};
const mapDispatchToProps = dispatch => ({
setKeyword: payload => dispatch(({type:'updateSearchText', keyword: payload }))
});
export default connect(
mapStateToProps,
mapDispatchToProps
)(SearchTextInput);
Solution 7 - Javascript
The problem is common happen when you have a complex page, that need re-render always that you update the state. So you can percept that is very slow when typing.
I found a solution: The cycle of life of react run by component. So you can create other component and manage yours events, like onChange, after you can call onBlur, that is passed by props for him. It worked for me:
import React, {Fragment, useState, useEffect} from 'react';
import TextField from '@material-ui/core/TextField';
export function InputText(props) {
const [value, setValue] = useState("");
const {onBlur = (e) => {console.log(e)}, name='name', defaultValue= 'Default', type='text', label='Label'} = props
useEffect(() => {
// console.log(value);
})
return (
<label>
<TextField
name={name}
label={label}
onBlur={e => onBlur(e)}
type={type}
value={value}
onChange={e => setValue(e.target.value)}
/>
</label>
);
}
class Sample extends React.Component {
handleBlurInput = e => {
this.setState({ [e.target.name]: e.target.value });
};
render() {
return (
<InputText name="nome" label="Label Sample" defaultValue={this.state.nome} onBlur={this.handleBlurInput.bind(this)} />
// Complex app ....
);
}
}