import * as React from 'react';
interface IData {
id: number,
title: string
}
interface IState {
checkedValues: Set<IData>;
data: IData[];
}
interface IProps {
value: IData,
checked: boolean,
onChange: (v: IData) => void
}
class ItemComp extends React.Component<IProps> {
shouldComponentUpdate(nextProps: IProps) {
const props = this.props;
return props.value !== nextProps.value || props.checked !== nextProps.checked
}
render() {
const { value, checked } = this.props;
return (
<label>
<input
type="checkbox"
checked={checked}
onChange={this.onChange} />
{value.title}
</label>
)
}
onChange = () => {
this.props.onChange(this.props.value);
}
}
// tslint:disable-next-line:max-classes-per-file
export default class App extends React.Component<{}, IState> {
constructor(props: {}) {
super(props)
const initValue: IState = {
checkedValues: new Set(),
data: []
}
for (let i = 0; i < 20000; i++) {
let temp = { id: Math.random(), title: i }
initValue.data.push(temp)
initValue.checkedValues.add(temp)
}
this.state = initValue;
}
render() {
const onChange = this.onChange;
const { checkedValues, data } = this.state;
return (
<div className="App">
{data.map((value) =>
<ItemComp
key={value.id}
value={value}
checked={checkedValues.has(value)}
onChange={onChange} />
)}
</div>
);
}
onChange = (active: IData) => {
const checkedValues = new Set(this.state.checkedValues);
if (checkedValues.has(active)) {
checkedValues.delete(active);
} else {
checkedValues.add(active);
}
this.setState({ checkedValues })
console.log(checkedValues)
}
}
比较慢的代码案例:
import React, { Component } from 'react';
import { Checkbox } from 'antd'
class App extends Component {
constructor(props) {
super(props)
this.state = {
checked: []
}
}
render() {
let list = this.list()
return (
<div>
{list}
</div>
);
}
}
Object.assign(App.prototype, {
componentDidMount() {
let arr = []
for (let i = 0; i < 20000; i++) {
arr.push(i)
}
this.setState({
checked: arr
})
},
list() {
let { checked } = this.state
let arr = []
for (let i = 0; i < 20000; i++) {
arr.push(<Checkbox key={i} checked={checked.indexOf(i) >= 0} onChange={this.handleChange.bind(this, i)}>{i}</Checkbox>)
}
return arr
},
handleChange(index, e) {
let { checked } = this.state
let tempIndex = checked.indexOf(index)
if (e.target.checked) {
if (tempIndex < 0) {
checked.push(index)
}
} else {
if (tempIndex >= 0) {
checked.splice(tempIndex, 1)
}
}
this.setState({
checked: checked
})
console.log(checked)
}
})
export default App