Home/ Questions/What is the typeerror: cannot read property 'apply' of undefined problem, and how to solve it?
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Ari Walsh
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Asked: 2022-05-18T20:19:38+00:00 In:

What is the typeerror: cannot read property ‘apply’ of undefined problem, and how to solve it?

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I encountered the following problem in completing my work:

TypeError: Cannot read property 'apply' of undefined

Below is the code I ran:

import { createStore, applyMiddleware,compose } from 'redux';
 import thunk from 'redux-thunk';
 import rootReducer from './reducers';
 
 const initialState={};
 
 const middleware = [thunk];
 
 const store = createStore(rootReducer,initialState,
  compose(
  applyMiddleware(...middleware),
  window.__REDUX_DEVTOOLS_EXTENSION__&& window.__REDUX_DEVTOOLS_EXTENSION__()
  ) 
  );
 
 
 export default store;
"@material-ui/core": "^3.3.1",
  "@material-ui/icons": "^3.0.1",
  "axios": "^0.18.0",
  "jwt-decode": "^2.2.0",
  "prop-types": "^15.6.2",
  "react": "^16.6.0",
  "react-dom": "^16.6.0",
  "react-redux": "^5.1.0",
  "react-router-dom": "^4.3.1",
  "react-scripts": "2.0.5",
  "react-select": "^2.1.1",
  "recharts": "^1.3.5",
  "redux": "^4.0.1",
  "redux-thunk": "^2.3.0",
  "typeface-roboto": "0.0.54"
"dependencies": {
  "bcryptjs": "^2.4.3",
  "body-parser": "^1.18.3",
  "express": "^4.16.4",
  "mongoose": "^5.3.11",
  "multer": "^1.4.1",
  "passport": "^0.4.0",
  "passport-jwt": "^4.0.0",
  "path": "^0.12.7",
  "validator": "^10.9.0",
  "xlsx": "^0.14.1"
  },
  "devDependencies": {
  "concurrently": "^4.0.1",
  "nodemon": "^1.18.6",
  },

What’s causing it, and how can it be resolved in the “typeerror: cannot read property ‘apply’ of undefined“ in the javascript?

cannot read property apply of undefined
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2 Answers

  1. Best Answer
    Expert

    The cause: This error happens because compose from redux wants all of its parameters to be functions. As a result,

    window.__REDUX_DEVTOOLS_EXTENSION__ && window.__REDUX_DEVTOOLS_EXTENSION__()

    returns a boolean when it is evaluated in that environment. 

    Solution: To solve this error, you’d have to return a function that doesn’t return anything.

    window.__REDUX_DEVTOOLS_EXTENSION__
  ? window.__REDUX_DEVTOOLS_EXTENSION__()
  : f => f
    • 0

  2. This was the same problem I encountered when I tried to test my web application on an incognito browser (extensions do not show up in incognito windows).

    compose from redux assumes that all arguments should be functions. What then? 

    window.__REDUX_DEVTOOLS_EXTENSION__ && window.__REDUX_DEVTOOLS_EXTENSION__()

    It returns a boolean if it is evaluated in this environment.

    @knutwalker pointed out. It would be necessary to return a function which returns nothing. It worked for me. 

     window.__REDUX_DEVTOOLS_EXTENSION__
 ? window.__REDUX_DEVTOOLS_EXTENSION__()
 : f => f
    • 24

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