Is it possible to run a function inside Phaser 3, this.input.on dragstart?

I am writing a game of Solitaire in Phaser 3 and want to run a function inside of this.input.on('dragstart', .... I can drag a single card inside of dragstart, but I need a function to work out which other cards to drag? I have declared the function like so:

getOtherCards(card)
{
    ...
}

I try to use getOtherCards inside of my dragstart, like so:

this.input.on('dragstart', function (pointer, card) {
    // Find all cards in this stack that should move together
    this.getOtherCards(card);
});

In my console I get an error saying getOtherCards has not been declared? My question is can I run a function like this inside of my dragstart, and if not, what is my alternative?

You have to pass the scope to the event function, just set the second argument to this (= the current scene):

this.input.on('dragstart', function (pointer, card) {
    // Find all cards in this stack that should move together
    this.getOtherCards(card);
}, this); // <-- Scope

Here is the link to the documentation.

An Alternative, can be to use an arrow function, than you will not need to pass the scope:

this.input.on('dragstart', (pointer, card) => {
    // Find all cards in this stack that should move together
    this.getOtherCards(card);
});