In React, a component is a piece of reusable UI code that can be rendered to the screen. It typically represents a small, self-contained part of a user interface and can accept data as input (props) and manage its own state. Components can be combined to build more complex UI, and th...
原文地址:https://facebook.github.io/react/docs/components-and-props.html 组件让您将UI拆分成独立的可重复使用的部分,并单独考虑每个部分。 在概念上,组件就像JavaScript函数。他们接受任意输入(称为“"props”),并返回应该在屏幕上显示的React元素描述。 一、Functional and Class Components 有两种方式创建组件:...
1. 从定义上来说, 组件就像JavaScript的函数。组件可以接收任意输入(称为”props”), 并返回 React 元素,用以描述屏幕显示内容。就像一个有返回值的带参函数。 2. 组件必须返回一个单独的根元素。 3.所有 React 组件都必须是纯函数,并禁止修改其自身 props 。
我们调用ReactDOM.render()与<Welcome name="Sara" />元素。 2. React调用Welcome组件{name: 'Sara'}作为道具。 3. 我们的Welcome组件返回一个Hello, Sara元素作为结果。 4. React DOM有效地更新DOM以匹配Hello, Sara。 警告: 始终用大写字母开始组件名称。例如,表示一个DOM标签,但<Welcome />表示一个组件,...
在之前,我们只遇到过用来代表DOM 标记的 React 元素(Element): constelement=; 然而,元素还可以用来代表自定义组件( user-defined components): constelement=<Welcomename="Sara"/>; 当React看到一个元素代表着自定义组件,它将会把JSX属性传入这个组件作为一个单一对象。我们把这个对象称为"props"。 例如这段...
React components use props to communicate with each other. Every parent component can pass some information to its child components by giving them props. Props might remind you of HTML attributes, but you can pass any JavaScript value through them, including objects, arrays, and functions. You ...
you will assign to the prop. JSX allows you to spread an object containing your named props into your Component which enables you to avoid the repetition of matching prop names and variable names. This lessons covers spreading JSX component props in both pure components and class components. ...
And supposedly you need the computed value for rendering. In this case, instead of doing: class Component extends React.Component { constructor(props) { super(props); this.state = { computed_prop: heavy_computation(props.value) }; } componentWillReceiveProps(newProps) { if (newProps.value ...
In this chapter, I describe the key building block in React applications: the component. I focus on the simplest type of component in this chapter, which is the stateless component. I describe the more complex alternative, stateful components, in Chapter 11. I also explain how the props ...
There’s one aspect of JavaScript that always has me pulling my hair: closures. I work with React a lot, and the overlap there is that they can sometimes be