You may optionally pass an object as the first argument tosetState()instead of a function: 开发者还可以在第一次参数的位置不传入函数,而是传入一个对象。 setState(stateChange[, callback]) This performs a shallow merge ofstateChangeinto the new state, e.g., to adjust a shopping cart item q...
setState函数允许接受两个参数,第一个是partialState,它可以是一个Object,也可以是一个function,也可以是一个空对象指针null,(这里的invariant是一个库,它的用法就是如果不满足第一个参数,则打印后面的错误信息,通常是开发环境中使用),中间部分pass,直接看底部,会发现有两个函数,enqueueSetState和enqueueCallback,enq...
enqueueSetState:function(inst,payload,callback){varfiber=get(inst);varcurrentTime=requestCurrentTimeForUpdate();varsuspenseConfig=requestCurrentSuspenseConfig();varexpirationTime=computeExpirationForFiber(currentTime,fiber,suspenseConfig);varupdate=createUpdate(expirationTime,suspenseConfig);update.payload=payload;...
may optionally pass an object as the first argument to setState()instead ofa function: setState(stateChange[, callback]) 翻译:你可以有选择性的传递一个对象作为setState的第一参数 解释:除了传递函数之外也可以使用对象作为参数 This performs a shallow merge of stateChangeinto thenew state, e.g., ...
root.render(<Title author="Peter" />); //调用组件时传Argument给组件 3.1.3 state 对象 如上例可见,Class组件的构造函数可以指定state对象; state 对象的访问和Function组件的Hook一样,[state, setState] = useState(); 读state对象需要用 this.state.prop 语句; ...
In this lesson we'll walk through setting up an updater function that can receive an action argument. We'll also dive into how to separate your state management logic into a separate reducer function much like how Redux operates. It will receive an action which we can add any data and upd...
React.createClass({ displayName: 'Counter', getDefaultProps: function(){ return {initialCount: 0}; }, getInitialState: function() { return {count: this.props.initialCount} }, propTypes: {initialCount: React.PropTypes.number}, tick() { this.setState({count: this.state.count + 1}); },...
这里是调用updater的enqueueSetState来执行逻辑的,这个updater是我们在beginWork的时候创建的,代码位于packages/react-reconciler/src/ReactFiberClassComponent.js: 代码语言:javascript 复制 functionadoptClassInstance(workInProgress:Fiber,instance:any):void{instance.updater=classComponentUpdater;workInProgress.stateNode=...
ReactUpdateQueue模块,一则作为用户自定义组件ReactComponent的参数updater,供ReactComponent实例的setState、replaceState、forceUpdate方法调用ReactUpdateQueue模块的方法,用于更新state,并重绘组件;一则为用户自定义组件ReactComponent提供isMount方法判断组件是否挂载完成;一则为ReactMount模块使用,在该模块中挂载设定用户自定义组...
And inside JSX, we use this.state.count to access the value of the state key we defined in the constructor to display the count. Setter is pretty much the same, just different syntax. Alternatively, you can write an onClick function. Remember, the setState function takes argument(s) of ...