React - Props
Table of Contents
About
props is the only object argument passed to a component
Props is similar to State, but it is public and not fully controlled by the component.
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Syntax
in React - JSX
<MyComponent name={javascriptVariable} color="Blue"/>
will create two props
- props.name
- and props.color
Requirements
Props:
- must be named from the component's own point of view rather than the context in which it is being used.
- are read-only. A component must never modify its own props. It must modify it via this.setState() <note important>All React components must act like pure functions with respect to their props.</note> See React - State
Management
Default value
Default values are defined by assigning to the special defaultProps property to the component.
- A class greeting component with one prop: name
class Greeting extends React.Component {
render() {
return (
<h1>Hello, {this.props.name}</h1>
);
}
}
- Specifies the default value for the name prop:
Greeting.defaultProps = {
name: 'Stranger (Default)'
};
- And render
ReactDOM.render(
<Greeting />,
document.getElementById('root')
);
<div id="root">
<!-- called the "root" DOM node because everything inside it will be managed by React DOM -->
</div>
Type checking
built-in Type checking in React is known as prop-types
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