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Firebase: Detecting if data exists. This snippet detects if a user ID is already taken
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function go() { | |
var userId = prompt('Username?', 'Guest'); | |
checkIfUserExists(userId); | |
} | |
var USERS_LOCATION = 'https://SampleChat.firebaseIO-demo.com/users'; | |
function userExistsCallback(userId, exists) { | |
if (exists) { | |
alert('user ' + userId + ' exists!'); | |
} else { | |
alert('user ' + userId + ' does not exist!'); | |
} | |
} | |
// Tests to see if /users/<userId> has any data. | |
function checkIfUserExists(userId) { | |
var usersRef = new Firebase(USERS_LOCATION); | |
usersRef.child(userId).once('value', function(snapshot) { | |
var exists = (snapshot.val() !== null); | |
userExistsCallback(userId, exists); | |
}); | |
} |
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