如何在React.js中执行debounce ?
我想撤消handleOnChange。
我尝试debounce(这。handleOnChange, 200)但它不起作用。
function debounce(fn, delay) {
var timer = null;
return function() {
var context = this,
args = arguments;
clearTimeout(timer);
timer = setTimeout(function() {
fn.apply(context, args);
}, delay);
};
}
var SearchBox = React.createClass({
render: function() {
return <input type="search" name="p" onChange={this.handleOnChange} />;
},
handleOnChange: function(event) {
// make ajax call
}
});
扩展useState钩子
import { useState } from "react";
import _ from "underscore"
export const useDebouncedState = (initialState, durationInMs = 500) => {
const [internalState, setInternalState] = useState(initialState);
const debouncedFunction = _.debounce(setInternalState, durationInMs);
return [internalState, debouncedFunction];
};
export default useDebouncedState;
使用钩
import useDebouncedState from "../hooks/useDebouncedState"
//...
const [usernameFilter, setUsernameFilter] = useDebouncedState("")
//...
<input id="username" type="text" onChange={e => setUsernameFilter(e.target.value)}></input>
https://trippingoncode.com/react-debounce-hook/
你也可以使用自己编写的mixin,就像这样:
var DebounceMixin = {
debounce: function(func, time, immediate) {
var timeout = this.debouncedTimeout;
if (!timeout) {
if (immediate) func();
this.debouncedTimeout = setTimeout(function() {
if (!immediate) func();
this.debouncedTimeout = void 0;
}.bind(this), time);
}
}
};
然后像这样在你的组件中使用它:
var MyComponent = React.createClass({
mixins: [DebounceMixin],
handleClick: function(e) {
this.debounce(function() {
this.setState({
buttonClicked: true
});
}.bind(this), 500, true);
},
render: function() {
return (
<button onClick={this.handleClick}></button>
);
}
});
你必须使用useCallback,正如在这篇博客中提到的:
https://www.freecodecamp.org/news/debounce-and-throttle-in-react-with-hooks/
import React, { useCallback } from 'react';
import debounce from 'debounce'; // or another package
function App() {
...
const debouncedSave = useCallback(
debounce(x => foo(x), 1000),
[], // will be created only once initially
);
...
}
你试过吗?
function debounce(fn, delay) {
var timer = null;
return function() {
var context = this,
args = arguments;
clearTimeout(timer);
timer = setTimeout(function() {
fn.apply(context, args);
}, delay);
};
}
var SearchBox = React.createClass({
render: function() {
return <input type="search" name="p" onChange={this.handleOnChange} />;
},
handleOnChange: function(event) {
debounce(\\ Your handleChange code , 200);
}
});
至于2021年6月,您可以简单地实现xnimorz解决方案:https://github.com/xnimorz/use-debounce
import { useState, useEffect, useRef } from "react";
// Usage
function App() {
// State and setters for ...
// Search term
const [searchTerm, setSearchTerm] = useState("");
// API search results
const [results, setResults] = useState([]);
// Searching status (whether there is pending API request)
const [isSearching, setIsSearching] = useState(false);
// Debounce search term so that it only gives us latest value ...
// ... if searchTerm has not been updated within last 500ms.
// The goal is to only have the API call fire when user stops typing ...
// ... so that we aren't hitting our API rapidly.
const debouncedSearchTerm = useDebounce(searchTerm, 500);
// Effect for API call
useEffect(
() => {
if (debouncedSearchTerm) {
setIsSearching(true);
searchCharacters(debouncedSearchTerm).then((results) => {
setIsSearching(false);
setResults(results);
});
} else {
setResults([]);
setIsSearching(false);
}
},
[debouncedSearchTerm] // Only call effect if debounced search term changes
);
return (
<div>
<input
placeholder="Search Marvel Comics"
onChange={(e) => setSearchTerm(e.target.value)}
/>
{isSearching && <div>Searching ...</div>}
{results.map((result) => (
<div key={result.id}>
<h4>{result.title}</h4>
<img
src={`${result.thumbnail.path}/portrait_incredible.${result.thumbnail.extension}`}
/>
</div>
))}
</div>
);
}
// API search function
function searchCharacters(search) {
const apiKey = "f9dfb1e8d466d36c27850bedd2047687";
return fetch(
`https://gateway.marvel.com/v1/public/comics?apikey=${apiKey}&titleStartsWith=${search}`,
{
method: "GET",
}
)
.then((r) => r.json())
.then((r) => r.data.results)
.catch((error) => {
console.error(error);
return [];
});
}
// Hook
function useDebounce(value, delay) {
// State and setters for debounced value
const [debouncedValue, setDebouncedValue] = useState(value);
useEffect(
() => {
// Update debounced value after delay
const handler = setTimeout(() => {
setDebouncedValue(value);
}, delay);
// Cancel the timeout if value changes (also on delay change or unmount)
// This is how we prevent debounced value from updating if value is changed ...
// .. within the delay period. Timeout gets cleared and restarted.
return () => {
clearTimeout(handler);
};
},
[value, delay] // Only re-call effect if value or delay changes
);
return debouncedValue;
}
使用React Hooks和响应式编程(RxJS)的React ajax debounce和cancel示例解决方案:
import React, { useEffect, useState } from "react";
import { ajax } from "rxjs/ajax";
import { debounceTime, delay, takeUntil } from "rxjs/operators";
import { Subject } from "rxjs/internal/Subject";
const App = () => {
const [items, setItems] = useState([]);
const [loading, setLoading] = useState(true);
const [filterChangedSubject] = useState(() => {
// Arrow function is used to init Singleton Subject. (in a scope of a current component)
return new Subject<string>();
});
useEffect(() => {
// Effect that will be initialized once on a react component init.
const subscription = filterChangedSubject
.pipe(debounceTime(200))
.subscribe((filter) => {
if (!filter) {
setLoading(false);
setItems([]);
return;
}
ajax(`https://swapi.dev/api/people?search=${filter}`)
.pipe(
// current running ajax is canceled on filter change.
takeUntil(filterChangedSubject)
)
.subscribe(
(results) => {
// Set items will cause render:
setItems(results.response.results);
},
() => {
setLoading(false);
},
() => {
setLoading(false);
}
);
});
return () => {
// On Component destroy. notify takeUntil to unsubscribe from current running ajax request
filterChangedSubject.next("");
// unsubscribe filter change listener
subscription.unsubscribe();
};
}, []);
const onFilterChange = (e) => {
// Notify subject about the filter change
filterChangedSubject.next(e.target.value);
};
return (
<div>
Cards
{loading && <div>Loading...</div>}
<input onChange={onFilterChange}></input>
{items && items.map((item, index) => <div key={index}>{item.name}</div>)}
</div>
);
};
export default App;