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JavaScript Understanding "this" in JavaScript

Leonardo Motta
Leonardo Motta
11,284 Points
Posted by Leonardo Motta
Leonardo Motta
11,284 Points

Why my template literals does not work with this arrow function?

const portland = {
  bridges: 12,
  airport: 1,
  soccerTeams:1,
  logNumberOfBridges: () => {
    console.log(`There are ${this.bridges} bridges in Portland!`)
  }
}

portland.logNumberOfBridges();

#############
###CONSOLE###
#############
leonardo@leo:~/firstApp$ node script.js
There are undefined bridges in Portland!

I found that without arrow function it works just as expected, but I am really confused here.

const portland = {
  bridges: 12,
  airport: 1,
  soccerTeams: 1,
  logNumberOfBridges: function() {
    console.log(`There are ${this.bridges} bridges in Portland!`)
  }
}
portland.logNumberOfBridges();

3 Answers

Steven Parker
Steven Parker
231,007 Points
Steven Parker
Steven Parker
231,007 Points

One of the ways arrow functions are different is that they do not define a "this" like conventional functions do.

For more details, see the MDN page on arrow functions.

Leonardo Motta
Leonardo Motta
11,284 Points
Leonardo Motta
Leonardo Motta
11,284 Points

You are always helping us, TY!

Daniel Stewart
Daniel Stewart
3,163 Points
Daniel Stewart
Daniel Stewart
3,163 Points

I think its the this binding of this one of the offsets about using arrow functions

Steven Parker
Steven Parker
231,007 Points
Steven Parker
Steven Parker
231,007 Points

I believe that's what I said!

Daniel Stewart
Daniel Stewart
3,163 Points
Daniel Stewart
Daniel Stewart
3,163 Points

Yes that is what you said i am allowed to comment. I am not saying your wrong