up.util up.util.isEqual.key

JavaScript property

This property contains the name of a method that user-defined classes may implement to hook into the up.util.isEqual() protocol.

Example

We have a user-defined Account class that we want to use with up.util.isEqual():

class Account {
  constructor(email) {
    this.email = email
  }

  [up.util.isEqual.key](other) {
    return this.email === other.email
  }
}

Note that the protocol method is not actually named 'up.util.isEqual.key'. Instead it is named after the value of the up.util.isEqual.key property. To do so, the code sample above is using a computed property name in square brackets.

We may now use Account instances with up.util.isEqual():

let one = new User('foo@foo.com')
let two = new User('foo@foo.com')
let three = new User('bar@bar.com')

up.util.isEqual(one, two)   // returns true
up.util.isEqual(one, three) // returns false