如何使用JavaScript从Firebase实时数据库中删除特定子项？

Question

i'm creating a game which stores it data in firebase database. Suppose When i touch a key it sets left:1 in database. How can i delete this left:1 when i remove the touch from that key.

The below code shows how i set left:1 in database.

document.getElementById('moveleft').addEventListener('touchstart',()=>{
        var left1 = left + 1;
        console.log(left1);

            var totalleft = firebase.database().ref('total left');

            totalleft.push({
                'left':left1
            });
            });

How can i delete this child(left) from the database when i remove the touch?

Answer 1

To delete a node from the database you'll need to have a reference to that node. The easiest way to do this, is to keep the reference in a variable in the touchstart handler:

var touchRef;
document.getElementById('moveleft').addEventListener('touchstart',()=>{

    var left1 = left + 1;
    console.log(left1);

    var totalleft = firebase.database().ref('total left');

    touchRef = totalleft.push({
        'left':left1
    });
});

And then in touchend handler you can use the reference to remove the nde:

document.getElementById('moveleft').addEventListener('touchend',()=>{
    touchRef.remove()
})