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react-is

19.1.0-canary-e03ac20f-20250305
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  • License MIT

Brand checking of React Elements.

Package Exports

    This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (react-is) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

    Readme

    react-is

    This package allows you to test arbitrary values and see if they're a particular React element type.

    Installation

    # Yarn
    yarn add react-is
    
    # NPM
    npm install react-is

    Usage

    Determining if a Component is Valid

    import React from "react";
    import * as ReactIs from "react-is";
    
    class ClassComponent extends React.Component {
      render() {
        return React.createElement("div");
      }
    }
    
    const FunctionComponent = () => React.createElement("div");
    
    const ForwardRefComponent = React.forwardRef((props, ref) =>
      React.createElement(Component, { forwardedRef: ref, ...props })
    );
    
    const Context = React.createContext(false);
    
    ReactIs.isValidElementType("div"); // true
    ReactIs.isValidElementType(ClassComponent); // true
    ReactIs.isValidElementType(FunctionComponent); // true
    ReactIs.isValidElementType(ForwardRefComponent); // true
    ReactIs.isValidElementType(Context.Provider); // true
    ReactIs.isValidElementType(Context.Consumer); // true

    Determining an Element's Type

    Context

    import React from "react";
    import * as ReactIs from 'react-is';
    
    const ThemeContext = React.createContext("blue");
    
    ReactIs.isContextConsumer(<ThemeContext.Consumer />); // true
    ReactIs.isContextProvider(<ThemeContext.Provider />); // true
    ReactIs.typeOf(<ThemeContext.Provider />) === ReactIs.ContextProvider; // true
    ReactIs.typeOf(<ThemeContext.Consumer />) === ReactIs.ContextConsumer; // true

    Element

    import React from "react";
    import * as ReactIs from 'react-is';
    
    ReactIs.isElement(<div />); // true
    ReactIs.typeOf(<div />) === ReactIs.Element; // true

    Fragment

    import React from "react";
    import * as ReactIs from 'react-is';
    
    ReactIs.isFragment(<></>); // true
    ReactIs.typeOf(<></>) === ReactIs.Fragment; // true

    Portal

    import React from "react";
    import ReactDOM from "react-dom";
    import * as ReactIs from 'react-is';
    
    const div = document.createElement("div");
    const portal = ReactDOM.createPortal(<div />, div);
    
    ReactIs.isPortal(portal); // true
    ReactIs.typeOf(portal) === ReactIs.Portal; // true

    StrictMode

    import React from "react";
    import * as ReactIs from 'react-is';
    
    ReactIs.isStrictMode(<React.StrictMode />); // true
    ReactIs.typeOf(<React.StrictMode />) === ReactIs.StrictMode; // true