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Quality Assurance Introduction to Selenium Automation Nation Page Object Model

Posted by Adam Travers
Adam Travers
568 Points

Could you elaborate on this please? const invitees = [...]; invitees.forEach(homePage.addInvitee, homePage);

I am unsure why homePage is places after the comma, what is it's purpose and function here specifically? 

 const invitees = [
    'Gonzalo Torres del Fierro',
    'Shadd Anderson',
    'George Aparece',
    'Shadab Khan',
    'Joseph Michael Casey',
    'Jennifer Nordell',
    'Faisal Albinali',
    'Taron Foxworth',
    'David Riesz',
    'Maicej Torbus',
    'Martin Luckett',
    'Joel Bardsley',
    'Reuben Varzea',
    'Ken Alger',
    'Amrit Pandey',
    'Rafal Rudzinski',
    'Brian Lynch',
    'Lupe Camacho',
    'Luke Fiji',
    'Sean Christensen',
    'Philip Graf',
    'Mike Norman',
    'Michael Hulet',
    'Brent Suggs'
 ];
  invitees.forEach(homePage.addInvitee, homePage);

1 Answer

Rohald van Merode
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STAFF
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Rohald van Merode
Treehouse Staff
Rohald van Merode
.a{fill-rule:evenodd;}techdegree
Rohald van Merode
Treehouse Staff

Hey Adam Travers 👋

Great question! That second parameter is used to specify the value of this in the addInvitee method.

The addInvitee function in the HomePage class relies on the values of this.driver and this.locators to interact with the page. Those two properties are available within the HomePage class itself but won't be available when the addInvitee function is called by forEach in index.js as the context will be different.

To make sure that those properties can be accessed within the addInvitee function you'll have to pass a second argument to the forEach. This will bind the this context to the correct homePage instance. Without it, the this keyword would not be tied to a specific object and it would default to the global object (window in browsers). Any references to this.driver and this.locators would then end up being undefined or be pointing to the wrong object 🙂

I hope this answers your question 😃 Happy coding!