why my program doesn't work when i define and describe the method of an object truck.drive()

I have a doubt on the following piece of code, which throws an error like syntax error, but the guide which i followed says that the syntax is correct. don’t know what to do, failed to understand, please help.

here is the code link:

const car = {
    maker: 'Ford',
    model: 'Fiesta',
  
    drive() {
      console.log(`Driving a ${this.maker} ${this.model} car!`)
    }
  }

car.drive()

// the same above code can be written as:
const bus = {
    maker: 'Ford',
    model: 'Bussie',
  
    drive: function() {
      console.log(`Driving a ${this.maker} ${this.model} bus!`)
    }
  }

bus.drive()

// the same code above can be written in this way:
const truck = {
    maker: 'Tata',
    model: 'Truckie',
  
    truck.drive = function() {
      console.log(`Driving a ${this.maker} ${this.model} truck!`)
    }
  }

truck.drive()

// Now, let us see how the arror function works:
const bike = {
    maker: 'Honda',
    model: 'Unicorn',
  
    drive: () => {
      console.log(`Driving a ${this.maker} ${this.model} bike!`)
    }
  }
  
bike.drive()

Error:

SyntaxError: Unexpected token '.'

at line: truck.drive = function() {

>Solution :

You probably misread. The equivalent code would be:

// the same code above can be written in this way:
const truck = {
  maker: 'Tata',
  model: 'Truckie'
}

truck.drive = function() {
  console.log(`Driving a ${this.maker} ${this.model} truck!`)
}

The assignment to truck.drive is after the initialization of truck, not inside the object literal.

First, you can’t put assignments inside an object literal, only property declarations. Second, you can’t refer to the variable being defined until after the assignment has completed.