{"id":6150,"date":"2022-05-16T08:39:21","date_gmt":"2022-05-16T00:39:21","guid":{"rendered":"https:\/\/www.lilichao.com\/?p=6150"},"modified":"2022-05-16T08:39:21","modified_gmt":"2022-05-16T00:39:21","slug":"react-memo","status":"publish","type":"post","link":"https:\/\/lilichao.com\/?p=6150","title":{"rendered":"React.memo"},"content":{"rendered":"\n

React\u7ec4\u4ef6\u4f1a\u5728\u4e24\u79cd\u60c5\u51b5\u4e0b\u53d1\u751f\u91cd\u65b0\u6e32\u67d3\u3002\u7b2c\u4e00\u79cd\uff0c\u5f53\u7ec4\u4ef6\u81ea\u8eab\u7684state\u53d1\u751f\u53d8\u5316\u65f6\u3002\u7b2c\u4e8c\u79cd\uff0c\u5f53\u7ec4\u4ef6\u7684\u7236\u7ec4\u4ef6\u91cd\u65b0\u6e32\u67d3\u65f6\u3002\u7b2c\u4e00\u79cd\u60c5\u51b5\u4e0b\u7684\u91cd\u65b0\u6e32\u67d3\u65e0\u53ef\u539a\u975e\uff0cstate\u90fd\u53d8\u4e86\uff0c\u7ec4\u4ef6\u81ea\u7136\u5e94\u8be5\u91cd\u65b0\u8fdb\u884c\u6e32\u67d3\u3002\u4f46\u662f\u7b2c\u4e8c\u79cd\u60c5\u51b5\u4f3c\u4e4e\u5e76\u4e0d\u662f\u603b\u90a3\u4e48\u7684\u5fc5\u8981\u3002<\/p>\n\n\n\n

\u6211\u4eec\u6765\u770b\u4e00\u4e2ademo\uff0c\u73b0\u6709\u5982\u4e0b\u4e09\u4e2a\u7ec4\u4ef6\uff0c\u5206\u522b\u4e3aApp\u7ec4\u4ef6\u3001A\u7ec4\u4ef6\u548cB\u7ec4\u4ef6\uff1a<\/p>\n\n\n\n

App.js<\/p>\n\n\n\n

const App = () => {\r\n    const [count, setCount] = useState(1);\r\n\r\n    const clickHandler = () => {\r\n        setCount(prevState => prevState + 1);\r\n    };\r\n\r\n    return (\r\n        <div>\r\n            <h2>App -- {count}<\/h2>\r\n            <button onClick={clickHandler}>\u589e\u52a0<\/button>\r\n\r\n            <A\/>\r\n        <\/div>\r\n    );\r\n};<\/code><\/pre>\n\n\n\n
A.js<\/p>\n\n\n\n
const A <\/em>= () => {
    const [count, setCount] = useState<\/em>(1);

    const clickHandler = () => {
      setCount(prevState => prevState + 1);
    };

    return (
        <div>
            <h2>\u7ec4\u4ef6A -- {count}<\/h2>
            <button onClick={clickHandler}>\u589e\u52a0<\/button>
            <B\/>
        <\/div>
    );
};

export default A<\/em>;<\/pre>\n\n\n\n
B.js<\/p>\n\n\n\n
const B <\/em>= () => {
    return (
        <div>
            <h2>\u7ec4\u4ef6B<\/h2>
        <\/div>
    );
};

export default B<\/em>;<\/pre>\n\n\n\n
\u4e09\u4e2a\u7ec4\u4ef6\u7684\u5f15\u7528\u5173\u7cfb\u4e3a\uff0cA\u7ec4\u4ef6\u662fApp\u7684\u5b50\u7ec4\u4ef6\u3001B\u7ec4\u4ef6\u662fA\u7ec4\u4ef6\u7684\u5b50\u7ec4\u4ef6\uff1aApp –> A –> B<\/p>\n\n\n\n
\u5f53App\u7ec4\u4ef6\u53d1\u751f\u91cd\u65b0\u6e32\u67d3\u65f6\uff0cA\u548cB\u7ec4\u4ef6\u90fd\u4f1a\u53d1\u751f\u91cd\u6e32\u67d3\u3002\u5f53A\u7ec4\u4ef6\u91cd\u65b0\u6e32\u67d3\u65f6\uff0cB\u7ec4\u4ef6\u4e5f\u4f1a\u91cd\u65b0\u6e32\u67d3\u3002B\u7ec4\u4ef6\u4e2d\u6ca1\u6709state\uff0c\u751a\u81f3\u8fdeprops\u90fd\u6ca1\u6709\u8bbe\u7f6e\u3002\u6362\u8a00\u4e4b\uff0cB\u7ec4\u4ef6\u65e0\u8bba\u5982\u4f55\u6e32\u67d3\uff0c\u6bcf\u6b21\u6e32\u67d3\u7684\u7ed3\u679c\u90fd\u662f\u76f8\u540c\u7684\uff0c\u867d\u7136\u91cd\u6e32\u67d3\u5e76\u4e0d\u4f1a\u5e94\u7528\u5230\u771f\u5b9eDOM\u4e0a\uff0c\u4f46\u5f88\u663e\u7136\u8fd9\u79cd\u6e32\u67d3\u662f\u5b8c\u5168\u6ca1\u6709\u5fc5\u8981\u7684\u3002<\/p>\n\n\n\n
\u4e3a\u4e86\u51cf\u5c11\u50cfB\u7ec4\u4ef6\u8fd9\u6837\u7ec4\u4ef6\u7684\u6e32\u67d3\uff0cReact\u4e3a\u6211\u4eec\u63d0\u4f9b\u4e86\u4e00\u4e2a\u65b9\u6cd5React.memo()<\/code>\u3002\u8be5\u65b9\u6cd5\u662f\u4e00\u4e2a\u9ad8\u9636\u51fd\u6570\uff0c\u53ef\u4ee5\u7528\u6765\u6839\u636e\u7ec4\u4ef6\u7684props\u5bf9\u7ec4\u4ef6\u8fdb\u884c\u7f13\u5b58\uff0c\u5f53\u4e00\u4e2a\u7ec4\u4ef6\u7684\u7236\u7ec4\u4ef6\u53d1\u751f\u91cd\u65b0\u6e32\u67d3\uff0c\u800c\u5b50\u7ec4\u4ef6\u7684props\u6ca1\u6709\u53d1\u751f\u53d8\u5316\u65f6\uff0c\u5b83\u4f1a\u76f4\u63a5\u5c06\u7f13\u5b58\u4e2d\u7684\u7ec4\u4ef6\u6e32\u67d3\u7ed3\u679c\u8fd4\u56de\u800c\u4e0d\u662f\u518d\u6b21\u89e6\u53d1\u5b50\u7ec4\u4ef6\u7684\u91cd\u65b0\u6e32\u67d3\uff0c\u8fd9\u6837\u4e00\u6765\u5c31\u5927\u5927\u7684\u964d\u4f4e\u4e86\u5b50\u7ec4\u4ef6\u91cd\u65b0\u6e32\u67d3\u7684\u6b21\u6570\u3002<\/p>\n\n\n\n
\u73b0\u5728\u5bf9\u4e0a\u8ff0\u6848\u4f8b\u4e2d\u7684B\u7ec4\u4ef6\u8fdb\u884c\u5982\u4e0b\u4fee\u6539\uff1a<\/p>\n\n\n\n
const B = () => {
    console.log('B\u6e32\u67d3');
    return (
        <div>
            <h2>\u7ec4\u4ef6B<\/h2>
        <\/div>
    );
};

export default React.memo<\/em>(B);<\/pre>\n\n\n\n
\u4fee\u6539\u540e\u7684\u4ee3\u7801\u4e2d\uff0c\u5e76\u6ca1\u6709\u76f4\u63a5\u5c06B\u7ec4\u4ef6\u5411\u5916\u5bfc\u51fa\uff0c\u800c\u662f\u5728B\u7ec4\u4ef6\u5916\u5c42\u5957\u4e86\u4e00\u5c42\u51fd\u6570React.memo()<\/code>\uff0c\u8fd9\u6837\u4e00\u6765\uff0c\u8fd4\u56de\u7684B\u7ec4\u4ef6\u5c31\u589e\u52a0\u4e86\u7f13\u5b58\u529f\u80fd\uff0c\u53ea\u6709\u5f53B\u7ec4\u4ef6\u7684props\u5c5e\u6027\u53d1\u751f\u53d8\u5316\u65f6\uff0c\u624d\u4f1a\u89e6\u53d1\u7ec4\u4ef6\u7684\u91cd\u65b0\u6e32\u67d3\u3002memo\u53ea\u4f1a\u6839\u636eprops\u5224\u65ad\u662f\u5426\u9700\u8981\u91cd\u65b0\u6e32\u67d3\uff0c\u548cstate\u548ccontext\u65e0\u5173\uff0cstate\u6216context\u53d1\u751f\u53d8\u5316\u65f6\uff0c\u7ec4\u4ef6\u4f9d\u7136\u4f1a\u6b63\u5e38\u7684\u8fdb\u884c\u91cd\u65b0\u6e32\u67d3\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
React\u7ec4\u4ef6\u4f1a\u5728\u4e24\u79cd\u60c5\u51b5\u4e0b\u53d1\u751f\u91cd\u65b0\u6e32\u67d3\u3002\u7b2c\u4e00\u79cd\uff0c\u5f53\u7ec4\u4ef6\u81ea\u8eab\u7684state\u53d1\u751f\u53d8\u5316\u65f6\u3002\u7b2c\u4e8c\u79cd\uff0c\u5f53\u7ec4\u4ef6\u7684\u7236\u7ec4\u4ef6\u91cd\u65b0 […]<\/p>\n","protected":false},"author":1,"featured_media":6154,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[198],"tags":[254,202],"_links":{"self":[{"href":"https:\/\/lilichao.com\/index.php?rest_route=\/wp\/v2\/posts\/6150"}],"collection":[{"href":"https:\/\/lilichao.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lilichao.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lilichao.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lilichao.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6150"}],"version-history":[{"count":2,"href":"https:\/\/lilichao.com\/index.php?rest_route=\/wp\/v2\/posts\/6150\/revisions"}],"predecessor-version":[{"id":6152,"href":"https:\/\/lilichao.com\/index.php?rest_route=\/wp\/v2\/posts\/6150\/revisions\/6152"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/lilichao.com\/index.php?rest_route=\/wp\/v2\/media\/6154"}],"wp:attachment":[{"href":"https:\/\/lilichao.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6150"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lilichao.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6150"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lilichao.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6150"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}