{"id":1112,"date":"2021-11-15T11:14:43","date_gmt":"2021-11-15T03:14:43","guid":{"rendered":"http:\/\/www.max-shu.com\/blog\/?p=1112"},"modified":"2021-11-15T11:19:00","modified_gmt":"2021-11-15T03:19:00","slug":"react%e5%9c%a816-8%e7%89%88%e6%9c%ac%e5%bc%80%e5%a7%8b%e5%a2%9e%e5%8a%a0hook%e6%94%af%e6%8c%81","status":"publish","type":"post","link":"http:\/\/www.max-shu.com\/blog\/?p=1112","title":{"rendered":"React\u572816.8\u7248\u672c\u5f00\u59cb\u589e\u52a0Hook\u652f\u6301"},"content":{"rendered":"

Hook \u662f React 16.8 \u7684\u65b0\u589e\u7279\u6027\u3002Hook \u662f\u4e00\u4e9b\u53ef\u4ee5\u8ba9\u4f60\u5728\u51fd\u6570\u7ec4\u4ef6\u91cc\u201c\u94a9\u5165\u201d React state \u53ca\u751f\u547d\u5468\u671f\u7b49\u7279\u6027\u7684\u51fd\u6570\u3002Hook \u4e0d\u80fd\u5728 class \u7ec4\u4ef6\u4e2d\u4f7f\u7528 \u2014\u2014 \u8fd9\u4f7f\u5f97\u4f60\u4e0d\u4f7f\u7528 class \u4e5f\u80fd\u4f7f\u7528 React\u3002<\/p>\n

\u4e3e\u4e2a\u4f8b\u5b50\uff1a<\/p>\n

import<\/span> React,<\/span> {<\/span> useState }<\/span> from<\/span> 'react'<\/span>;<\/span>\r\n\r\nfunction<\/span> Example<\/span>(<\/span>)<\/span> {<\/span>\r\n  \/\/ \u58f0\u660e\u4e00\u4e2a\u65b0\u7684\u53eb\u505a \u201ccount\u201d \u7684 state \u53d8\u91cf<\/span><\/span>  \r\n  const<\/span> [<\/span>count,<\/span> setCount]<\/span> =<\/span> useState<\/span>(<\/span>0<\/span>)<\/span>;<\/span><\/span>\r\n  return<\/span> (<\/span>\r\n    <<\/span>div><\/span><\/span>\r\n      <<\/span>p><\/span><\/span>You clicked <\/span>{<\/span>count}<\/span> times<\/span><\/<\/span>p><\/span><\/span>\r\n      <<\/span>button onClick<\/span>=<\/span>{<\/span>(<\/span>)<\/span> =><\/span> setCount<\/span>(<\/span>count +<\/span> 1<\/span>)<\/span>}<\/span><\/span>><\/span><\/span>\r\n        Click me<\/span>\r\n      <\/<\/span>button><\/span><\/span>\r\n    <\/<\/span>div><\/span><\/span>\r\n  )<\/span>;<\/span>\r\n}<\/span><\/code><\/pre>\n
\u5728\u8fd9\u91cc\uff0cuseState<\/code>\u00a0\u5c31\u662f\u4e00\u4e2a\u00a0Hook<\/em>\u00a0\u3002\u901a\u8fc7\u5728\u51fd\u6570\u7ec4\u4ef6\u91cc\u8c03\u7528\u5b83\u6765\u7ed9\u7ec4\u4ef6\u6dfb\u52a0\u4e00\u4e9b\u5185\u90e8 state\u3002React \u4f1a\u5728\u91cd\u590d\u6e32\u67d3\u65f6\u4fdd\u7559\u8fd9\u4e2a state\u3002useState<\/code>\u00a0\u4f1a\u8fd4\u56de\u4e00\u5bf9\u503c\uff1a\u5f53\u524d<\/strong>\u72b6\u6001\u548c\u4e00\u4e2a\u8ba9\u4f60\u66f4\u65b0\u5b83\u7684\u51fd\u6570\uff0c\u4f60\u53ef\u4ee5\u5728\u4e8b\u4ef6\u5904\u7406\u51fd\u6570\u4e2d\u6216\u5176\u4ed6\u4e00\u4e9b\u5730\u65b9\u8c03\u7528\u8fd9\u4e2a\u51fd\u6570\u3002\u5b83\u7c7b\u4f3c class \u7ec4\u4ef6\u7684\u00a0this.setState<\/code>\uff0c\u4f46\u662f\u5b83\u4e0d\u4f1a\u628a\u65b0\u7684 state \u548c\u65e7\u7684 state \u8fdb\u884c\u5408\u5e76\u3002<\/p>\n
\u00a0useState<\/code>\u00a0\u552f\u4e00\u7684\u53c2\u6570\u5c31\u662f\u521d\u59cb state\u3002\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0c\u6211\u4eec\u7684\u8ba1\u6570\u5668\u662f\u4ece\u96f6\u5f00\u59cb\u7684\uff0c\u6240\u4ee5\u521d\u59cb state \u5c31\u662f\u00a00<\/code>\u3002\u503c\u5f97\u6ce8\u610f\u7684\u662f\uff0c\u4e0d\u540c\u4e8e\u00a0this.state<\/code>\uff0c\u8fd9\u91cc\u7684 state \u4e0d\u4e00\u5b9a\u8981\u662f\u4e00\u4e2a\u5bf9\u8c61 \u2014\u2014 \u5982\u679c\u4f60\u6709\u9700\u8981\uff0c\u5b83\u4e5f\u53ef\u4ee5\u662f\u3002\u8fd9\u4e2a\u521d\u59cb state \u53c2\u6570\u53ea\u6709\u5728\u7b2c\u4e00\u6b21\u6e32\u67d3\u65f6\u4f1a\u88ab\u7528\u5230\u3002<\/p>\n
\u00a0useEffect<\/code>\u00a0\u662f\u4e00\u4e2a Effect Hook\uff0c\u7ed9\u51fd\u6570\u7ec4\u4ef6\u589e\u52a0\u4e86\u64cd\u4f5c\u526f\u4f5c\u7528\u7684\u80fd\u529b\u3002\u5b83\u8ddf class \u7ec4\u4ef6\u4e2d\u7684\u00a0componentDidMount<\/code>\u3001componentDidUpdate<\/code>\u00a0\u548c\u00a0componentWillUnmount<\/code>\u00a0\u5177\u6709\u76f8\u540c\u7684\u7528\u9014\uff0c\u53ea\u4e0d\u8fc7\u88ab\u5408\u5e76\u6210\u4e86\u4e00\u4e2a API\u3002<\/p>\n
\u4f8b\u5982\uff1a<\/p>\n
import<\/span> React,<\/span> {<\/span> useState,<\/span> useEffect }<\/span> from<\/span> 'react'<\/span>;<\/span><\/span>\r\nfunction<\/span> Example<\/span>(<\/span>)<\/span> {<\/span>\r\n  const<\/span> [<\/span>count,<\/span> setCount]<\/span> =<\/span> useState<\/span>(<\/span>0<\/span>)<\/span>;<\/span>\r\n\r\n  \/\/ \u76f8\u5f53\u4e8e componentDidMount \u548c componentDidUpdate:<\/span><\/span>  \r\n  useEffect<\/span>(<\/span>(<\/span>)<\/span> =><\/span> {\r\n<\/span><\/span>    \/\/ \u4f7f\u7528\u6d4f\u89c8\u5668\u7684 API \u66f4\u65b0\u9875\u9762\u6807\u9898\r\n<\/span><\/span>    document.<\/span>title =<\/span> `<\/span>You clicked <\/span>${<\/span>count}<\/span><\/span> times<\/span>`<\/span><\/span>;\r\n<\/span><\/span>  }<\/span>)<\/span>;<\/span><\/span>\r\n  return<\/span> (<\/span>\r\n    <<\/span>div><\/span><\/span>\r\n      <<\/span>p><\/span><\/span>You clicked <\/span>{<\/span>count}<\/span> times<\/span><\/<\/span>p><\/span><\/span>\r\n      <<\/span>button onClick<\/span>=<\/span>{<\/span>(<\/span>)<\/span> =><\/span> setCount<\/span>(<\/span>count +<\/span> 1<\/span>)<\/span>}<\/span><\/span>><\/span><\/span>\r\n        Click me<\/span>\r\n      <\/<\/span>button><\/span><\/span>\r\n    <\/<\/span>div><\/span><\/span>\r\n  )<\/span>;<\/span>\r\n}<\/span><\/code> \r\n\r\n\u5f53\u4f60\u8c03\u7528\u00a0useEffect\u00a0\u65f6\uff0c\u5c31\u662f\u5728\u544a\u8bc9 React \u5728\u5b8c\u6210\u5bf9 DOM \u7684\u66f4\u6539\u540e\u8fd0\u884c\u4f60\u7684\u201c\u526f\u4f5c\u7528\u201d\u51fd\u6570\u3002\u7531\u4e8e\u526f\u4f5c\u7528\u51fd\u6570 \r\n\u662f\u5728\u7ec4 \u4ef6\u5185\u58f0\u660e\u7684\uff0c\u6240\u4ee5\u5b83\u4eec\u53ef\u4ee5\u8bbf\u95ee\u5230\u7ec4\u4ef6\u7684 props \u548c state\u3002\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0cReact \u4f1a\u5728\u6bcf\u6b21\u6e32\u67d3\u540e\u8c03\u7528\u526f\u4f5c \r\n\u7528\u51fd\u6570 \u2014\u2014\u00a0\u5305 \u62ec\u7b2c\u4e00\u6b21\u6e32\u67d3\u7684\u65f6\u5019\u3002 \u526f\u4f5c\u7528\u51fd\u6570\u8fd8\u53ef\u4ee5\u901a\u8fc7\u8fd4\u56de\u4e00\u4e2a\u51fd\u6570\u6765\u6307\u5b9a\u5982\u4f55\u201c\u6e05\u9664\u201d\u526f\u4f5c\u7528\u3002\u4f8b\u5982\uff0c\u5728\u4e0b \r\n\u9762\u7684\u7ec4\u4ef6\u4e2d\u4f7f\u7528\u526f\u4f5c\u7528 \u51fd\u6570\u6765\u8ba2\u9605\u597d\u53cb\u7684\u5728\u7ebf\u72b6\u6001\uff0c\u5e76\u901a\u8fc7\u53d6\u6d88\u8ba2\u9605\u6765\u8fdb\u884c\u6e05\u9664\u64cd\u4f5c\uff1a<\/pre>\n
import<\/span> React,<\/span> {<\/span> useState,<\/span> useEffect }<\/span> from<\/span> 'react'<\/span>;<\/span>\r\n\r\nfunction<\/span> FriendStatus<\/span>(<\/span>props<\/span>)<\/span> {<\/span>\r\n  const<\/span> [<\/span>isOnline,<\/span> setIsOnline]<\/span> =<\/span> useState<\/span>(<\/span>null<\/span>)<\/span>;<\/span>\r\n\r\n  function<\/span> handleStatusChange<\/span>(<\/span>status<\/span>)<\/span> {<\/span>\r\n    setIsOnline<\/span>(<\/span>status.<\/span>isOnline)<\/span>;<\/span>\r\n  }<\/span>\r\n\r\n  useEffect<\/span>(<\/span>(<\/span>)<\/span> =><\/span> {\r\n<\/span><\/span>    ChatAPI.<\/span>subscribeToFriendStatus<\/span>(<\/span>props.<\/span>friend.<\/span>id,<\/span> handleStatusChange)<\/span>;\r\n<\/span><\/span>    return<\/span> (<\/span>)<\/span> =><\/span> {\r\n<\/span><\/span>      ChatAPI.<\/span>unsubscribeFromFriendStatus<\/span>(<\/span>props.<\/span>friend.<\/span>id,<\/span> handleStatusChange)<\/span>;\r\n<\/span><\/span>    }<\/span>;\r\n<\/span><\/span>  }<\/span>)<\/span>;<\/span><\/span>\r\n  if<\/span> (<\/span>isOnline ===<\/span> null<\/span>)<\/span> {<\/span>\r\n    return<\/span> 'Loading...'<\/span>;<\/span>\r\n  }<\/span>\r\n  return<\/span> isOnline ?<\/span> 'Online'<\/span> :<\/span> 'Offline'<\/span>;<\/span>\r\n}<\/span><\/code><\/pre>\n
Hook \u5c31\u662f JavaScript \u51fd\u6570\uff0c\u4f46\u662f\u4f7f\u7528\u5b83\u4eec\u4f1a\u6709\u4e24\u4e2a\u989d\u5916\u7684\u89c4\u5219\uff1a<\/p>\n
    \n
  • \u53ea\u80fd\u5728\u51fd\u6570\u6700\u5916\u5c42<\/strong>\u8c03\u7528 Hook\u3002\u4e0d\u8981\u5728\u5faa\u73af\u3001\u6761\u4ef6\u5224\u65ad\u6216\u8005\u5b50\u51fd\u6570\u4e2d\u8c03\u7528\u3002<\/li>\n
  • \u53ea\u80fd\u5728\u00a0React \u7684\u51fd\u6570\u7ec4\u4ef6<\/strong>\u4e2d\u8c03\u7528 Hook\u3002\u4e0d\u8981\u5728\u5176\u4ed6 JavaScript \u51fd\u6570\u4e2d\u8c03\u7528\u3002\uff08\u8fd8\u6709\u4e00\u4e2a\u5730\u65b9\u53ef\u4ee5\u8c03\u7528 Hook \u2014\u2014 \u5c31\u662f\u81ea\u5b9a\u4e49\u7684 Hook \u4e2d\uff09<\/li>\n<\/ul>\n
    \u8fd8\u6709\u4e00\u4e9b\u5176\u4ed6\u5185\u7f6e\u7684hook\uff1a\u6bd4\u5982useContext\u3001useReducer\u7b49\u7b49\u3002<\/p>\n
     <\/p>\n","protected":false},"excerpt":{"rendered":"
    Hook \u662f React 16.8 \u7684\u65b0\u589e\u7279\u6027\u3002Hook \u662f\u4e00\u4e9b\u53ef\u4ee5\u8ba9\u4f60\u5728\u51fd\u6570\u7ec4\u4ef6\u91cc\u201c\u94a9\u5165\u201d React st …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[63,13],"tags":[844,843,846,845],"class_list":["post-1112","post","type-post","status-publish","format-standard","hentry","category-63","category-13","tag-hook","tag-react","tag-usestate","tag-845"],"views":1385,"_links":{"self":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1112","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1112"}],"version-history":[{"count":5,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1112\/revisions"}],"predecessor-version":[{"id":1117,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1112\/revisions\/1117"}],"wp:attachment":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1112"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1112"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1112"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}