每次击键后反应输入失去焦点

Question

我的导航部件上有个搜索栏。每次击键后，输入将失去焦点，您必须重新单击它才能键入下一个键。

以下是输入：

<input
    type="text"
    name="search"
    placeholder="Search"
    value={search}
    onChange={handleInputChange}
/>

下面是handleInputChange函数：

function handleInputChange(event) {
   event.preventDefault();
   let value = event.target.value;
   setSearch(value);
}

下面是设置搜索的钩子：

const [search, setSearch] = useState("");

我尝试在输入中添加一个键，但这不起作用。当我将搜索输入移动到一个新组件时，这也不起作用。

以下是完整的代码：

import React, { useEffect, useState, useCallback } from "react";
import PropTypes from 'prop-types';
import { useSelector } from 'react-redux';
import AppBar from '@material-ui/core/AppBar';
import Toolbar from '@material-ui/core/Toolbar';
import { Row, Col } from '../Grid';
import IconButton from '@material-ui/core/IconButton';
import SearchIcon from '@material-ui/icons/Search';
import ShoppingCartOutlinedIcon from '@material-ui/icons/ShoppingCartOutlined';
import MenuIcon from '@material-ui/icons/Menu';
import Badge from '@material-ui/core/Badge';
import useScrollTrigger from '@material-ui/core/useScrollTrigger';
import Slide from '@material-ui/core/Slide';
import SideMenu from '../SideMenu';
import { MuiThemeProvider, createMuiTheme } from '@material-ui/core/styles';
import { toast } from 'react-toastify';
import 'react-toastify/dist/ReactToastify.css';
import { css } from 'glamor';
import "./style.css";


function Navbar(props) {
    const cart = useSelector(state => state.cart);
    const [cartTotal, setCartTotal] = useState(0);
    const [loggedIn, setLoggedIn] = useState(false);
    const [search, setSearch] = useState("");
    const [isOpen, setIsOpen] = useState(false);
    const [renderMiddleCol, setMiddleCol] = useState(true);
    const [menuClass, setMenuClass] = useState("no-menu");

    useEffect(() => {
        if (cart[0]) {
            setCartTotal(cart[0].line_items.length)
        }
    }, [cart[0]]);
    useEffect(() => {
        if (window.sessionStorage.id) {
            setLoggedIn(true);
        } else {
            setLoggedIn(false);
        }
    }, [loggedIn]);
    useEffect(() => {
        if (window.innerWidth < 450) {
            setMiddleCol(false);
        } else {
            setMiddleCol(true);
        }
    }, [window.innerWidth]);
    function HideOnScroll(props) {
        const { children, window } = props;
        const trigger = useScrollTrigger({ target: window ? window() : undefined });
        return (
            <Slide appear={false} direction="down" in={!trigger}>
                {children}
            </Slide>
        );
    }
    HideOnScroll.propTypes = {
        children: PropTypes.element.isRequired,
        window: PropTypes.func,
    };
    function CheckCart() {
        if (window.sessionStorage.id) {
            window.location.href = "/cart";
        } else {
            toast("Please login to view your cart", {
                className: css({
                    background: '#3E0768',
                    boxShadow: '2px 2px 20px 2px rgba(0,0,0,0.3)',
                    borderRadius: '17px'
                }),
                bodyClassName: css({
                    fontSize: '20px',
                    color: 'white'
                }),
                progressClassName: css({
                    background: "linear-gradient(90deg, rgba(0,0,0,1) 0%, rgba(62,7,104,1) 80%)"
                })
            });
        }
    }
    function Search() {
        if (search) {
            sessionStorage.setItem("search", search);
            window.location.href = "/search";
        } else {
            toast("Search field cannot be empty", {
                className: css({
                    background: '#3E0768',
                    boxShadow: '2px 2px 20px 2px rgba(0,0,0,0.3)',
                    borderRadius: '17px'
                }),
                bodyClassName: css({
                    fontSize: '20px',
                    color: 'white'
                }),
                progressClassName: css({
                    background: "linear-gradient(90deg, rgba(0,0,0,1) 0%, rgba(62,7,104,1) 80%)"
                })
            });
        }
    }
    function logOut(event) {
        event.preventDefault();
        setIsOpen(false);
        sessionStorage.clear();
        window.location.href = "/login";
    }
    function handleInputChange(event) {
        event.preventDefault();
        let value = event.target.value;
        setSearch(value);
    }
    function toggleMenu(event) {
        event.preventDefault();
        setIsOpen(!isOpen);
        if (menuClass === "no-menu") {
            setMenuClass("menu-background");
        } else {
            setMenuClass("no-menu");
        }
    }
    const theme = createMuiTheme({
        palette: {
            primary: {
                main: '#000000',
                contrastText: '#ffffff',
            },
            secondary: {
                light: '#3E0768',
                main: '#3E0768',
                contrastText: '#ffffff',
            },
            tertiary: {
                main: '#ffffff',
            }
        },
    });

    return (
        <MuiThemeProvider theme={theme}>
            <HideOnScroll {...props}>
                <AppBar position="fixed" color="primary">
                    <Toolbar>
                        <Col size="md-1">
                            <IconButton
                                onClick={toggleMenu}
                                aria-label="Menu"
                            >
                                <MenuIcon
                                    fontSize="large"
                                    className="white"
                                />
                            </IconButton>
                        </Col>
                        <Col size="md-2">
                            <a href="/" className="white "><h6>Demo Company</h6></a>
                        </Col>
                        {renderMiddleCol ? (
                            <Col size="lg-6 md-5 sm-3" />
                        ) : (<div />)}
                        <Col size="md-2 4">
                            <Row no-gutters>
                                <div className="search-box">
                                    <Col size="md-2 1">
                                        <IconButton onClick={Search} aria-label="search" >
                                            <SearchIcon className="white" />
                                        </IconButton>
                                    </Col>
                                    <Col size="md-8 9">
                                        {/* <SearchForm
                                            value={search}
                                            onChange={handleInputChange}
                                        /> */}
                                        <input
                                            className="search-field white"
                                            type="text"
                                            name="search"
                                            placeholder="Search"
                                            value={search}
                                            onChange={handleInputChange}
                                        />
                                    </Col>
                                </div>
                            </Row>
                        </Col>
                        <Col size="md-1">
                            <IconButton
                                onClick={CheckCart}
                                aria-label="Go to cart"
                            >
                                <MuiThemeProvider theme={theme}>
                                    <Badge
                                        badgeContent={cartTotal}
                                        color="secondary"
                                    >
                                        <ShoppingCartOutlinedIcon className="white" />
                                    </Badge>
                                </MuiThemeProvider>
                            </IconButton>
                        </Col>
                    </Toolbar>
                </AppBar>
            </HideOnScroll>
            <SideMenu
                isOpen={isOpen}
                menuClass={menuClass}
                toggleMenu={toggleMenu}
                loggedIn={loggedIn}
                logOut={logOut}
            />
        </MuiThemeProvider>
    );
}

export default Navbar;

Answer 1

最后，我在输入上使用了一个ref，并将它的焦点设置在每个重呈现上。这是修复它的代码。

const [search, setSearch] = useState("");
const searchInput = React.useRef(null);
useEffect(() => {
  searchInput.current.focus();
}, [search]);

以下是输入：

<input
  ref={searchInput}
  className="search-field white"
  type="text"
  name="search"
  placeholder="Search"
  value={search}
  onChange={handleInputChange}
/>

解决方案的功劳：React: set focus on componentDidMount, how to do it with hooks?

Answer 2

下面是我发现有帮助的详细解释：https://reactkungfu.com/2015/09/react-js-loses-input-focus-on-typing/

总结一下:如果没有一个不变的键，React就是在状态改变时丢弃您控制的输入的先前实例，并在其位置上创建一个新的实例。有焦点的输入在其值更改后立即被移除。

确保：

• 您的受控输入具有key属性
• key的值不是以任何方式从输入的value派生的，因为您不希望在值更改

时更改键

Answer 3

我不知道具体原因，但我的焦点问题通过更改代码解决了：

import { Route } from 'react-router-dom'
<Route path='xxx' component={() => <TheComponent... />}

其中，TheComponent包含输入元素，该元素在键入时失去焦点，对应于以下代码：

<Route path='xxx'>
  <TheComponent... />
</Route>

看看my SO question，希望有人很快就能了解到这是怎么回事