`this` is not being bound in prototype method

Question

I have some weird issue an arrow function:

Arrow functions are supposed to have a context of this bound when in a prototype method (es6 class method in this case), but in this case the 'this' is undef inside the 1st lambda

 apply(bookings) {
    if (!bookings.length) {
      return
    }
    bookings.forEach(booking=> {

  //this is undef here

      let matchingTimeSlot = this.timeSlots.find(item=>item.bookingDate.isSame(booking.bookingDate))
    })

apply is being called from another es6 class:

this.days[i].apply(currentDaysBookings);

Show us how you call `apply`, please. I'm sure `this` is `undefined` outside of the arrow function as well. — Bergi, Mar 19 '16 at 13:46
Arrow functions are not supposed to have `this` "bound" to anything. No, they are supposed to have *the same `this`* as their lexical parent function. — Bergi, Mar 19 '16 at 13:47
How do you know? You're not using it, are you? Are you sure that `currentDaysBookings` is defined? — Bergi, Mar 19 '16 at 16:30
@Bergi I'm sure, I used a debugger, yes `currentDaysBookings` is defined — SuperUberDuper, Mar 19 '16 at 22:46

score 2 · Accepted Answer · answered Mar 22 '16 at 05:17

2

this is undef here

Please note that your debug tools might be lying to you. this will actually get transpiled to _this or something like that. You should look at the generated JavaScript. I can assure you that it will have _this (or whatever its called) pointing to the right thing.

answered Mar 22 '16 at 05:17

basarat

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Ok I noticed that _this is correct, so the bug is in babel then? Why wouldn't babel transpile it to this? How am I supposed to know its _this? – SuperUberDuper Mar 29 '16 at 16:19
so now I need to change my code from `this.timeSlots ` to `_this.timeSlots `, this seems very sad.. – SuperUberDuper Mar 29 '16 at 16:34

`this` is not being bound in prototype method

1 Answers1