TypeError: Cannot read property 'timeout' of undefined with Mocha and Fat Arrow Syntax

  • Posted on: 12 July 2016
  • By: davis

Don't do this: 

describe('Do Something', () => {
  it(`Should do stuff successfully`, (done) => {
    // *this* binding refers to parent function scope in fat arrow functions
    // this will fail, no pun intended

    // do stuff here and include done() in the callback

Replace it with a normal function - fat arrow syntax will assign the "wrong" scope to timeout(), and you'll get an error like TypeError: Cannot read property 'timeout' of undefined