Anonymous function: 'this' inside doesn't work

Question

Lets say I have this code, with normal function:

let a = {
  parent: "roger",
  child: "bear",

  printName: function() {
    console.log(`${this.parent} ${this.child}`)
  }
}

b = {
  parent: "float",
  child: "bear",
}

a.printName.call(b)

The output is as expected:

float bear

However, the same code with anonymous function doesn't work:

let a = {
  parent: "roger",
  child: "bear",

  printName: () => {
    console.log(`${this.parent} ${this.child}`)
  }
}

b = {
  parent: "float",
  child: "bear",
}

a.printName.call(b)

This results in:

undefined undefined

Even passing 'this' to anonymous doesn't seem to work:

let a = {
    parent: "roger",
    child: "bear",

    printName: (this) => {
        console.log(`${this.parent} ${this.child}`)
    }
}

This results in a syntax error: Unexpected token this

Questions:

• Please explain why is this happening?
• How to get it to work?