{"id":187462,"date":"2020-11-06T12:55:10","date_gmt":"2020-11-06T04:55:10","guid":{"rendered":"http:\/\/4563.org\/?p=187462"},"modified":"2020-11-06T12:55:10","modified_gmt":"2020-11-06T04:55:10","slug":"react-useeffect-%e9%87%8c%e9%9d%a2%e7%9a%84%e8%ae%a1%e6%95%b0%e5%99%a8%ef%bc%8c%e5%a6%82%e4%bd%95%e5%9c%a8%e8%be%be%e5%88%b0%e6%8c%87%e5%ae%9a%e6%95%b0%e5%ad%97%e5%90%8e%ef%bc%8c%e5%81%9c%e6%ad%a2","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=187462","title":{"rendered":"react useEffect \u91cc\u9762\u7684\u8ba1\u6570\u5668\uff0c\u5982\u4f55\u5728\u8fbe\u5230\u6307\u5b9a\u6570\u5b57\u540e\uff0c\u505c\u6b62\u4e0b\u6765\uff1f"},"content":{"rendered":"
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react useEffect \u91cc\u9762\u7684\u8ba1\u6570\u5668\uff0c\u5982\u4f55\u5728\u8fbe\u5230\u6307\u5b9a\u6570\u5b57\u540e\uff0c\u505c\u6b62\u4e0b\u6765\uff1f <\/h1>\n

<\/p>\n

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\u8cc7\u6df1\u5927\u4f6c : yazoox <\/span> <\/i> 2<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
<\/p>\n

\u8fd9\u4e2a\u662f\u5b98\u65b9\u7684\u4e00\u4e2a\u4f8b\u5b50\uff0c\u6211\u6539\u4e86\u4e00\u4e0b\uff0c\u80fd\u591f\u6b63\u5e38\u8ba1\u6570\uff0c\u4ece 100 \u5f00\u59cb\u5012\u6570\u3002
\u8bf7\u95ee\uff0c\u5982\u4f55\u5728 count === 0 \u7684\u65f6\u5019\uff0c\u505c\u6b62\u5237\u65b0 \/\u8ba1\u6570\uff1f<\/p>\n

import React, { useState, useEffect } from \"react\";  export default function Counter() {   const [count, setCount] = useState(100);    useEffect(() => {     const id = setInterval(() => {       setCount((c) => c - 1);     }, 1000);     return () => clearInterval(id);   }, []);    return <h1>{count}<\/h1>; } <\/code><\/pre>\n
refer to: https:\/\/react.docschina.org\/docs\/hooks-faq.html#what-do-hooks-mean-for-popular-apis-like-redux-connect-and-react-router<\/p>\n<\/p><\/div>\n
 \u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (6<\/span>)        <\/div>\n
 <\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : dxhuii <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u8bd5\u8bd5\u8fd9\u6837<\/p>\n
    “`js
    import React, { useState, useEffect } from “react”;<\/p>\n
    export default function Counter() {
     const [count, setCount] = useState(10);<\/p>\n
     useEffect(() => {
     const id = setInterval(() => {
     setCount((c) => c – 1);
     }, 1000);
     if (count === 0) {
     clearInterval(id);
     console.log(“\u6267\u884c\u5230\u4e86\u8fd9\u91cc”);
     }<\/p>\n
     return () => clearInterval(id);
     }, [count]);<\/p>\n
     return <h1>{count}<\/h1>;
    }
    “`                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : syfless <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u628a\u90a3\u884c setCount \u6362\u6210\u8fd9\u4e2a\u5c31\u884c
    “`js
    “`                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : syfless <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u628a\u90a3\u884c setCount \u6362\u6210\u8fd9\u4e2a\u5c31\u884c
    “`js
    setCount((c) => {
     if (c > 5) {
     return c – 1;
     }
     clearInterval(id);
     return c;
     });
    “`                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : yihouzenmeban <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
     \"react <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u8cc7\u6df1\u5927\u4f6c : funnyecho <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4e0d\u7528 setInterval\uff0c\u7528 setTimeout + useEffect \u5c31\u597d<\/p>\n
    useEffect(() => {
     if (count <= 0) return<\/p>\n
     const id = setTimeout(() => {
     setCount((c) => c – 1);
     }, 1000);<\/p>\n
     return () => clearInterval(id);
     }, [count]);                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : yazoox <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @funnyecho \u8fd9\u4e2a\u53ef\u4ee5\u5de5\u4f5c<\/p>\n
    @dxhuii \u8fd9\u4e2a\u53ef\u80fd\u5de5\u4f5c<\/p>\n
    @syfless \u8fd9\u4e2a\u4e5f\u53ef\u80fd\u5de5\u4f5c\u3002\u4e0d\u8fc7\uff0c\u6700\u540e\u5f53 c <= 5 \u65f6\uff0c\u6ca1\u6709\u8fd4\u56de\u503c\uff0c\u8fd9\u65f6\uff0ccount \u597d\u50cf\u88ab\u8bbe\u7f6e\u6210\u4e86 undefined \u3002UI \u4e0a\u539f\u6765\u663e\u793a\u6570\u5b57\u5012\u8ba1\u65f6\u7684\uff0c\u6700\u540e\u5c31\u6d88\u5931\u4e86\u3002<\/p>\n
    \u8c22\u8c22\u5927\u5bb6\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"
    react useEffect \u91cc…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/187462"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=187462"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/187462\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=187462"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=187462"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=187462"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}