letisOnline =true;// if else statement.if(isOnline){console.log("He is Online.");}else{console.log("He is Offline.");}//He is Online //Same example using the ternary operator[condition] ? [if] : [else]isOnline ?
babel-standalone内置了Babel的核心功能和常用插件,可以直接在浏览器中引用,由此直接在浏览器中使用babel来转换Js代码。 在这里实际上我们在这里用的是babel 6.x,babel-standalone也就是6.x版本的min.js包才791KB,而@babel/standalone也就是7.x版本的min.js包已经2.77MB了,只不过7.x版本会有TS直接类型定义@ty...
// ref: react-16.2.0/build/packages/react/index.jsif(process.env.NODE_ENV==='production'){module.exports=require('./cjs/react.production.min.js');}else{module.exports=require('./cjs/react.development.js');} 常用手段,构建时把process.env.NODE_ENV替换成目标环境对应的字符串常量,在后续构建...
if the element not found index is -1if(indexOfAvocado!=-1){console.log('This fruit does exist in the array')}else{console.log('This fruit does not exist in the
Changing any environment variables will require you to restart the development server if it is running. These environment variables will be defined for you on process.env. For example, having an environment variable named REACT_APP_SECRET_CODE will be exposed in your JS as process.env.REACT_APP...
This will make moduleA.js and all its unique dependencies as a separate chunk that only loads after the user clicks the 'Load' button. You can also use it with async / await syntax if you prefer it. With React Router If you are using React Router check out this tutorial on how to ...
If you need if...else chains or the switch statement instead, it should "just work", but look up Discriminated Unions if you need help. (See also: Basarat's writeup). This is handy in typing reducers for useReducer or Redux. Optional Types If a component has an optional prop, add a...
error); } else if (result.isCancelled) { console.log("login is cancelled."); } else { if (Platform.OS === "ios") { AuthenticationToken.getAuthenticationTokenIOS().then((data) => { console.log(data?.authenticationToken); }); } else { AccessToken.getCurrentAccessToken().then((data)...
Changing any environment variables will require you to restart the development server if it is running. These environment variables will be defined for you on process.env. For example, having an environment variable named REACT_APP_SECRET_CODE will be exposed in your JS as process.env.REACT_APP...
It would still be imported from src/index.js, but you could always remove that import if you later migrate to a different build tool.Adding a CSS Modules StylesheetNote: this feature is available with react-scripts@2.0.0 and higher.