![javascript - Undefined is not an object (evaluating 'React.PropTypes.Number') error - Stack Overflow javascript - Undefined is not an object (evaluating 'React.PropTypes.Number') error - Stack Overflow](https://i.stack.imgur.com/9okLC.png)
javascript - Undefined is not an object (evaluating 'React.PropTypes.Number') error - Stack Overflow
undefined is not an ovject (evaluating '_react.PropTypes.string') · Issue #2009 · aksonov/react-native-router-flux · GitHub
![Cannot read property 'string' of undefined · Issue #2517 · aksonov/react-native-router-flux · GitHub Cannot read property 'string' of undefined · Issue #2517 · aksonov/react-native-router-flux · GitHub](https://user-images.githubusercontent.com/11005451/31672726-984dcfa0-b35d-11e7-9e7d-d354b47e3694.png)
Cannot read property 'string' of undefined · Issue #2517 · aksonov/react-native-router-flux · GitHub
undefined is not an object evaluating ReactPropTypes.string · Issue #14590 · facebook/react-native · GitHub
![undefined is not an object (evaluating '_react3.default.PropTypes.string') · Issue #966 · FaridSafi/react-native-gifted-chat · GitHub undefined is not an object (evaluating '_react3.default.PropTypes.string') · Issue #966 · FaridSafi/react-native-gifted-chat · GitHub](https://user-images.githubusercontent.com/43063849/45212786-b1ec8200-b28d-11e8-9c69-2b182b8b3505.png)
undefined is not an object (evaluating '_react3.default.PropTypes.string') · Issue #966 · FaridSafi/react-native-gifted-chat · GitHub
![How TypeScript helps us prevent the most common error in JavaScript development | by Kevin Gelpes | Medium How TypeScript helps us prevent the most common error in JavaScript development | by Kevin Gelpes | Medium](https://miro.medium.com/v2/resize:fit:818/1*MNvsifPzXkS57rKwvDHQMw.png)
How TypeScript helps us prevent the most common error in JavaScript development | by Kevin Gelpes | Medium
![types/prop-types and @types/react] PropTypes.shape throws type errors and incorrectly insists on PropTypes.exact · Issue #34692 · DefinitelyTyped/DefinitelyTyped · GitHub types/prop-types and @types/react] PropTypes.shape throws type errors and incorrectly insists on PropTypes.exact · Issue #34692 · DefinitelyTyped/DefinitelyTyped · GitHub](https://user-images.githubusercontent.com/4138285/77814546-f57d2b80-707f-11ea-9001-74b7c02b85c0.png)