On my database i have a variable called user points, and i want to increase that variable by a value, lets say by 10, everytime i want.
I am doing this:
on firebase:
update({userPoints: +pointsToGet})
i am using the + to increase the value, but its not working. Is there any way that i can increase the userPoints without using the variable user points like this : userPoints = userPoints + pointsToGet
i tried using ++pointsToGet but it didnt work either
Yes you can by using firebase.firestore.FieldValue.increment(...).
update({ userPoints: firebase.firestore.FieldValue.increment(pointsToGet) })
For more information check out this tutorial: https://fireship.io/snippets/firestore-increment-tips/
Or for the official docs, here: https://firebase.google.com/docs/reference/js/firebase.firestore.FieldValue#static-increment
No there is no solution for that, I would recommend you to stick to the following:
update({ userPoints: oldUserPoints + pointsToGet })
Or check out this answer, where someone explains how to do this with a transaction (which is better for race conditions): https://stackoverflow.com/a/40405392/9150652
Also just for your information, +pointsToGet returns the numeric value of your variable (which probably already is a number, so it will just return that number).
It is not used to add 1 to a variable. You can transform a string to a number with it. I hope the following snippet explains it a little:
const createLog = (result) => { // Just a helper, so that we can see the "" for strings in the console
return JSON.stringify({result});
}
console.log(createLog( '123' ));
console.log(createLog( +'123' ));
console.log(createLog( '123' + '123' ));
console.log(createLog( +'123' + +'123' ));