Firebase database remove() "is not a function" - firebase-realtime-database

Question

This code works:
firebase.database().ref($scope.language).orderByChild('word').equalTo($scope.word).once('value')
.then(function(snapshot) {
console.log(snapshot.val());
})
It logs the object and its key.
This code doesn't work:
firebase.database().ref($scope.language).orderByChild('word').equalTo($scope.word).remove()
.then(function(snapshot) {
console.log("Removed!");
})
The error message is:
TypeError: firebase.database(...).ref(...).orderByChild(...).equalTo(...).remove is not a function
The documentation makes remove() look simple. What am I missing?

Answer 1

You can only load data once you know its specific location in the JSON tree. To determine that location, you need to execute the query and loop through the matching results:
firebase.database().ref($scope.language).orderByChild('word').equalTo($scope.word).once("value").then(function(snapshot) {
snapshot.forEach(function(child) {
child.ref.remove();
console.log("Removed!");
})
});
If you only want to log after all have been removed, you can use Promise.all():
firebase.database().ref($scope.language).orderByChild('word').equalTo($scope.word).once("value").then(function(snapshot) {
var promises = [];
snapshot.forEach(function(child) {
promises.push(child.ref.remove());
})
Promise.all(promises).then(function() {
console.log("All removed!");
})
});

Answer 2

This is Frank's first code block with another closure. Without the closure the record is removed from the database but then there's an error message:
Uncaught (in promise) TypeError: snapshot.forEach(...).then is not a function
Adding a closure fixes the error message.
firebase.database().ref($scope.language).orderByChild('word').equalTo($scope.word).once("value").then(function(snapshot) {
snapshot.forEach(function(child) {
child.ref.remove();
}); // a closure is needed here
}).then(function() {
console.log("Removed!");
});