第一次点击 React Router Link 时 document.querySelector() 总是 return null,但之后会 return 正确
document.querySelector() always return null when clicking on React Router Link the first time but will return correctly after
我遇到了 React-Router 和 querySelector 的问题。
我有一个 Navbar
组件,其中包含用于导航的所有 CustomLink
组件和一个线条动画,它侦听这些组件并根据当前活动组件显示动画。
// Navbar.tsx
import React, { useCallback, useEffect, useState, useRef } from "react";
import { Link, useLocation } from "react-router-dom";
import CustomLink from "./Link";
const Layout: React.FC = ({ children }) => {
const location = useLocation();
const navbarRef = useRef<HTMLDivElement>(null);
const [pos, setPos] = useState({ left: 0, width: 0 });
const handleActiveLine = useCallback((): void => {
if (navbarRef && navbarRef.current) {
const activeNavbarLink = navbarRef.current.querySelector<HTMLElement>(
".tdp-navbar__item.active"
);
console.log(activeNavbarLink);
if (activeNavbarLink) {
setPos({
left: activeNavbarLink.offsetLeft,
width: activeNavbarLink.offsetWidth,
});
}
}
}, []);
useEffect(() => {
handleActiveLine();
}, [location]);
return (
<>
<div className="tdp-navbar-content shadow">
<div ref={navbarRef} className="tdp-navbar">
<div className="tdp-navbar__left">
<p>Todo+</p>
<CustomLink to="/">About</CustomLink>
<CustomLink to="/login">Login</CustomLink>
</div>
<div className="tdp-navbar__right">
<button className="tdp-button tdp-button--primary tdp-button--border">
<div className="tdp-button__content">
<Link to="/register">Register</Link>
</div>
</button>
<button className="tdp-button tdp-button--primary tdp-button--default">
<div className="tdp-button__content">
<Link to="/login">Login</Link>
</div>
</button>
</div>
<div
className="tdp-navbar__line"
style={{ left: pos.left, width: pos.width }}
/>
</div>
</div>
<main className="page">{children}</main>
</>
);
};
export default Layout;
// CustomLink.tsx
import React, { useEffect, useState } from "react";
import { useLocation, useHistory } from "react-router-dom";
interface Props {
to: string;
}
const CustomLink: React.FC<Props> = ({ to, children }) => {
const location = useLocation();
const history = useHistory();
const [active, setActive] = useState(false);
useEffect(() => {
if (location.pathname === to) {
setActive(true);
} else {
setActive(false);
}
}, [location, to]);
return (
// eslint-disable-next-line react/button-has-type
<button
className={`tdp-navbar__item ${active ? "active" : ""}`}
onClick={(): void => {
history.push(to);
}}
>
{children}
</button>
);
};
export default CustomLink;
但它并不如我所愿。所以我打开 Chrome Devtool 并调试,我意识到当我先点击一个 CustomLink
时, Navbar
的 querySelector()
将 return 为空。但是如果我多次点击同一个CustomLink
,它会正常return,就像下面的截图:
Error from Chrome Console
我怎样才能第一次从 querySelector()
得到正确的 return?谢谢!
因为handleActiveLine
会在CustomLink.tsx
的setActive(true)
之前触发
在CustomLink.tsx
中添加回调:
const CustomLink: React.FC<Props> = ({ onActive }) => {
useEffect(() => {
if (active) {
onActive();
}
}, [active]);
}
在Navbar.tsx
中:
const Layout: React.FC = ({ children }) => {
function handleOnActive() {
// do your query selector here
}
// add onActive={handleOnActive} to each CustomLink
return <CustomLink onActive={handleOnActive} />
}
我遇到了 React-Router 和 querySelector 的问题。
我有一个 Navbar
组件,其中包含用于导航的所有 CustomLink
组件和一个线条动画,它侦听这些组件并根据当前活动组件显示动画。
// Navbar.tsx
import React, { useCallback, useEffect, useState, useRef } from "react";
import { Link, useLocation } from "react-router-dom";
import CustomLink from "./Link";
const Layout: React.FC = ({ children }) => {
const location = useLocation();
const navbarRef = useRef<HTMLDivElement>(null);
const [pos, setPos] = useState({ left: 0, width: 0 });
const handleActiveLine = useCallback((): void => {
if (navbarRef && navbarRef.current) {
const activeNavbarLink = navbarRef.current.querySelector<HTMLElement>(
".tdp-navbar__item.active"
);
console.log(activeNavbarLink);
if (activeNavbarLink) {
setPos({
left: activeNavbarLink.offsetLeft,
width: activeNavbarLink.offsetWidth,
});
}
}
}, []);
useEffect(() => {
handleActiveLine();
}, [location]);
return (
<>
<div className="tdp-navbar-content shadow">
<div ref={navbarRef} className="tdp-navbar">
<div className="tdp-navbar__left">
<p>Todo+</p>
<CustomLink to="/">About</CustomLink>
<CustomLink to="/login">Login</CustomLink>
</div>
<div className="tdp-navbar__right">
<button className="tdp-button tdp-button--primary tdp-button--border">
<div className="tdp-button__content">
<Link to="/register">Register</Link>
</div>
</button>
<button className="tdp-button tdp-button--primary tdp-button--default">
<div className="tdp-button__content">
<Link to="/login">Login</Link>
</div>
</button>
</div>
<div
className="tdp-navbar__line"
style={{ left: pos.left, width: pos.width }}
/>
</div>
</div>
<main className="page">{children}</main>
</>
);
};
export default Layout;
// CustomLink.tsx
import React, { useEffect, useState } from "react";
import { useLocation, useHistory } from "react-router-dom";
interface Props {
to: string;
}
const CustomLink: React.FC<Props> = ({ to, children }) => {
const location = useLocation();
const history = useHistory();
const [active, setActive] = useState(false);
useEffect(() => {
if (location.pathname === to) {
setActive(true);
} else {
setActive(false);
}
}, [location, to]);
return (
// eslint-disable-next-line react/button-has-type
<button
className={`tdp-navbar__item ${active ? "active" : ""}`}
onClick={(): void => {
history.push(to);
}}
>
{children}
</button>
);
};
export default CustomLink;
但它并不如我所愿。所以我打开 Chrome Devtool 并调试,我意识到当我先点击一个 CustomLink
时, Navbar
的 querySelector()
将 return 为空。但是如果我多次点击同一个CustomLink
,它会正常return,就像下面的截图:
Error from Chrome Console
我怎样才能第一次从 querySelector()
得到正确的 return?谢谢!
因为handleActiveLine
会在CustomLink.tsx
的setActive(true)
之前触发
在CustomLink.tsx
中添加回调:
const CustomLink: React.FC<Props> = ({ onActive }) => {
useEffect(() => {
if (active) {
onActive();
}
}, [active]);
}
在Navbar.tsx
中:
const Layout: React.FC = ({ children }) => {
function handleOnActive() {
// do your query selector here
}
// add onActive={handleOnActive} to each CustomLink
return <CustomLink onActive={handleOnActive} />
}