问题：

为什么使用状态在javascript中不起作用？

彭修筠

2023-03-14

我试图使用反应组件在我的超文本标记语言

在下面的例子中，它在不使用状态的情况下工作得很好

https://jsbin.com/paduyarase/edit?html输出

现在我在我的组件中引入usestate。我编译了下面的函数，使用的是javascript，但它不起作用。

import React from 'react';

const Index = () => {
    const [state,setState] = React.useState(0)
  return (
      <div>
        hello World {state}
      </div>
  );
};

export default Index;

此组件不工作https://jsbin.com/hefiretaru/edit?html输出

获取错误

错误：缩小的反应错误#321；参观https://reactjs.org/docs/error-decoder.html?invariant=321 获取完整消息，或使用非小型开发环境获取完整错误和其他有用警告。在L（：10:4000）在Object.useState（：10:5366）在t.default（：2:1777）在renderWithHooks(https://unpkg.com/react-dom@17.0.1/umd/react dom.development.js:15015:20）位于MountIndendenceComponent(https://unpkg.com/react-dom@17.0.1/umd/react dom.development.js:17841:15）在开始工作时(https://unpkg.com/react-dom@17.0.1/umd/react dom.development.js:19079:18）在HTMLUnknownElement.callCallback(https://unpkg.com/react-dom@17.0.1/umd/react dom.development.js:3942:16）位于Object.invokeGuardedCallbackDev(https://unpkg.com/react-dom@17.0.1/umd/react dom.development.js:3991:18）在invokeGuardedCallback(https://unpkg.com/react-dom@17.0.1/umd/react dom.development.js:4053:33）在beginWork$1(https://unpkg.com/react-dom@17.0.1/umd/react dom.development.js:23994:9）VM178:10未捕获错误：缩小反应错误#321；访问https://reactjs.org/docs/error-decoder.html?invariant=321 对于完整消息，或使用非小型开发环境获取完整错误和其他有用警告。在L（：10:4000）在Object.useState（：10:5366）在t.default（：2:1777）在renderWithHooks（vmdom.development.js:15015）

代码

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <script src="https://unpkg.com/react@17.0.1/umd/react.development.js"></script>
    <script src="https://unpkg.com/react-dom@17.0.1/umd/react-dom.development.js"></script>
   <script>
     !function(e,t){"object"==typeof exports&&"object"==typeof module?module.exports=t():"function"==typeof define&&define.amd?define([],t):"object"==typeof exports?exports.MyCom=t():e.MyCom=t()}(window,(function(){return function(e){var t={};function r(n){if(t[n])return t[n].exports;var o=t[n]={i:n,l:!1,exports:{}};return e[n].call(o.exports,o,o.exports,r),o.l=!0,o.exports}return r.m=e,r.c=t,r.d=function(e,t,n){r.o(e,t)||Object.defineProperty(e,t,{enumerable:!0,get:n})},r.r=function(e){"undefined"!=typeof Symbol&&Symbol.toStringTag&&Object.defineProperty(e,Symbol.toStringTag,{value:"Module"}),Object.defineProperty(e,"__esModule",{value:!0})},r.t=function(e,t){if(1&t&&(e=r(e)),8&t)return e;if(4&t&&"object"==typeof e&&e&&e.__esModule)return e;var n=Object.create(null);if(r.r(n),Object.defineProperty(n,"default",{enumerable:!0,value:e}),2&t&&"string"!=typeof e)for(var o in e)r.d(n,o,function(t){return e[t]}.bind(null,o));return n},r.n=function(e){var t=e&&e.__esModule?function(){return e.default}:function(){return e};return r.d(t,"a",t),t},r.o=function(e,t){return Object.prototype.hasOwnProperty.call(e,t)},r.p="",r(r.s=1)}([function(e,t,r){"use strict";e.exports=r(2)},function(e,t,r){"use strict";r.r(t);var n=r(0),o=r.n(n);function u(e,t){return function(e){if(Array.isArray(e))return e}(e)||function(e,t){if(!(Symbol.iterator in Object(e)||"[object Arguments]"===Object.prototype.toString.call(e)))return;var r=[],n=!0,o=!1,u=void 0;try{for(var c,f=e[Symbol.iterator]();!(n=(c=f.next()).done)&&(r.push(c.value),!t||r.length!==t);n=!0);}catch(e){o=!0,u=e}finally{try{n||null==f.return||f.return()}finally{if(o)throw u}}return r}(e,t)||function(){throw new TypeError("Invalid attempt to destructure non-iterable instance")}()}t.default=function(){var e=u(o.a.useState(0),2),t=e[0];e[1];return o.a.createElement("div",null,"hello World ",t)}},function(e,t,r){"use strict";
/** @license React v16.12.0
 * react.production.min.js
 *
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
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u="";null!=r&&(u=(""+r).replace($,"$&/")+"/"),I(e,U,t=A(t,u,n,o)),M(t)}function L(){var e=w.current;if(null===e)throw Error(v(321));return e}var N={Children:{map:function(e,t,r){if(null==e)return e;var n=[];return F(e,n,null,t,r),n},forEach:function(e,t,r){if(null==e)return e;I(e,T,t=A(null,null,t,r)),M(t)},count:function(e){return I(e,(function(){return null}),null)},toArray:function(e){var t=[];return F(e,t,null,(function(e){return e})),t},only:function(e){if(!E(e))throw Error(v(143));return e}},createRef:function(){return{current:null}},Component:g,PureComponent:_,createContext:function(e,t){return void 0===t&&(t=null),(e={$$typeof:s,_calculateChangedBits:t,_currentValue:e,_currentValue2:e,_threadCount:0,Provider:null,Consumer:null}).Provider={$$typeof:a,_context:e},e.Consumer=e},forwardRef:function(e){return{$$typeof:p,render:e}},lazy:function(e){return{$$typeof:b,_ctor:e,_status:-1,_result:null}},memo:function(e,t){return{$$typeof:d,type:e,compare:void 0===t?null:t}},useCallback:function(e,t){return L().useCallback(e,t)},useContext:function(e,t){return L().useContext(e,t)},useEffect:function(e,t){return L().useEffect(e,t)},useImperativeHandle:function(e,t,r){return L().useImperativeHandle(e,t,r)},useDebugValue:function(){},useLayoutEffect:function(e,t){return L().useLayoutEffect(e,t)},useMemo:function(e,t){return L().useMemo(e,t)},useReducer:function(e,t,r){return L().useReducer(e,t,r)},useRef:function(e){return L().useRef(e)},useState:function(e){return L().useState(e)},Fragment:f,Profiler:i,StrictMode:l,Suspense:y,createElement:C,cloneElement:function(e,t,r){if(null==e)throw Error(v(267,e));var o=n({},e.props),c=e.key,f=e.ref,l=e._owner;if(null!=t){if(void 0!==t.ref&&(f=t.ref,l=x.current),void 0!==t.key&&(c=""+t.key),e.type&&e.type.defaultProps)var i=e.type.defaultProps;for(a in t)k.call(t,a)&&!P.hasOwnProperty(a)&&(o[a]=void 0===t[a]&&void 0!==i?i[a]:t[a])}var a=arguments.length-2;if(1===a)o.children=r;else if(1<a){i=Array(a);for(var s=0;s<a;s++)i[s]=arguments[s+2];o.children=i}return{$$typeof:u,type:e.type,key:c,ref:f,props:o,_owner:l}},createFactory:function(e){var t=C.bind(null,e);return t.type=e,t},isValidElement:E,version:"16.12.0",__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED:{ReactCurrentDispatcher:w,ReactCurrentBatchConfig:{suspense:null},ReactCurrentOwner:x,IsSomeRendererActing:{current:!1},assign:n}},D={default:N},V=D&&N||D;e.exports=V.default||V},function(e,t,r){"use strict";
/*
object-assign
(c) Sindre Sorhus
@license MIT
*/var n=Object.getOwnPropertySymbols,o=Object.prototype.hasOwnProperty,u=Object.prototype.propertyIsEnumerable;function c(e){if(null==e)throw new TypeError("Object.assign cannot be called with null or undefined");return Object(e)}e.exports=function(){try{if(!Object.assign)return!1;var e=new String("abc");if(e[5]="de","5"===Object.getOwnPropertyNames(e)[0])return!1;for(var t={},r=0;r<10;r++)t["_"+String.fromCharCode(r)]=r;if("0123456789"!==Object.getOwnPropertyNames(t).map((function(e){return t[e]})).join(""))return!1;var n={};return"abcdefghijklmnopqrst".split("").forEach((function(e){n[e]=e})),"abcdefghijklmnopqrst"===Object.keys(Object.assign({},n)).join("")}catch(e){return!1}}()?Object.assign:function(e,t){for(var r,f,l=c(e),i=1;i<arguments.length;i++){for(var a in r=Object(arguments[i]))o.call(r,a)&&(l[a]=r[a]);if(n){f=n(r);for(var s=0;s<f.length;s++)u.call(r,f[s])&&(l[f[s]]=r[f[s]])}}return l}}])}));
  </script>
    <title>React App</title>
</head>
<body>
    <div id="root"></div>
    <script>
        ReactDOM.render(
          React.createElement(MyCom.default),
          document.getElementById('root')
        );
      </script>
</body>
</html>

卢志强

2023-03-14

迷你React错误#321通常意味着你有两个相互冲突的React版本。在编辑器中搜索"react"：。如果找到两个版本（16.8和17.0），则问题已修复。

如果不是关于重复，请删除类组件的render（）中的任何注释。

为什么使用状态在javascript中不起作用？

共有1个答案

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