Uncaught ReferenceError: React is not defined

Question

I am trying to make ReactJS work with rails using this tutorial. I am getting this error:

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Uncaught ReferenceError: React is not defined

Answer 1

The displayed error

after that import react

Finally import react-dom

if error is react is not define,please add ==>import React from 'react';

if error is reactDOM is not define,please add ==>import ReactDOM from 'react-dom';

Answer 2

I got this error because I was using

import ReactDOM from 'react-dom'

without importing react, once I changed it to below:

import React from 'react';
import ReactDOM from 'react-dom';

The error was solved :)

Answer 3

I was facing the same issue. I resolved it by importing React and ReactDOM like as follows:

import React from 'react';
import ReactDOM from 'react-dom';

Answer 4

Try to add:

import React from 'react'
import { render } from 'react-dom'
window.React = React

before the render() function.

This sometimes prevents error to pop-up returning:

React is not defined

Adding React to the window will solve these problems.

Answer 5

I got this error because in my code I misspelled a component definition with lowercase react.createClass instead of uppercase React.createClass.

Answer 6

import React, { Component, PropTypes } from 'react';

This may also work!