6 replies

Parent and child constructors

if I have a UserForm class:

class UserForm extends View {
    // no constructor
}

class UserForm extends View {
    // no constructor
}

and a View class:

class View {
  constructor(parentElement){ this.parentElement = parentElement }
}

class View {
  constructor(parentElement){ this.parentElement = parentElement }
}

Does anyone know why

new UserForm('root')

new UserForm('root')

causes the UserForm class to inherit the View constructor and set the

parentElement

parentElement

variable correctly? Definitely wasn't the behavior I was expecting

My best guess is that behind the scenes

UserForm

UserForm

is creating a new object from the

View

View

's prototype, and because one isn't present in the

UserForm

UserForm

class it inherits it rather than overriding it if it had been explicitly provided - that would also explain why I don't have to call

super

super

in this case to set View properties? This is all a guess though, it's been a while since I've looked at prototype inheritance, and this seems like a bit of an edge case that's not included often

KP-C

Kevin Powell - Community•3y ago•

6 replies

JWode

Parent and child constructors

if I have a UserForm class:

class UserForm extends View {
    // no constructor
}

class UserForm extends View {
    // no constructor
}

and a View class:

class View {
  constructor(parentElement){ this.parentElement = parentElement }
}

class View {
  constructor(parentElement){ this.parentElement = parentElement }
}

Does anyone know why

new UserForm('root')

new UserForm('root')

causes the UserForm class to inherit the View constructor and set the

parentElement

parentElement

variable correctly? Definitely wasn't the behavior I was expecting

My best guess is that behind the scenes

UserForm

UserForm

is creating a new object from the

View

View

's prototype, and because one isn't present in the

UserForm

UserForm

class it inherits it rather than overriding it if it had been explicitly provided - that would also explain why I don't have to call

super

super

in this case to set View properties? This is all a guess though, it's been a while since I've looked at prototype inheritance, and this seems like a bit of an edge case that's not included often

Parent and child constructors

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