Executing JavaScript code sequentially

Question

Executing JavaScript code sequentially

I've been running into an issue with my JavaScript code not executing in the expected order. It seems to be skipping straight to the if(!hadError) condition before handling any errors that may occur, resulting in hadError always being true. I understand that this has to do with how JavaScript runs things asynchronously, but I'm unsure of how to resolve it. Here's the code snippet:


var email = $('#email').val();
var password = $('#password').val();
var hadError = false;

if(email != "" && password != ""){
  auth.signInWithEmailAndPassword(email, password).catch(function(error) {
    hadError = true;
    console.log(hadError);
    var errorCode = error.code;
    var errorMessage = error.message;
    $('#login-error').text(errorMessage);    
  });
  if(!hadError){
    success();
  }
}

javascript ajax firebase firebase-authentication

Answer 1

Answer №1

When working with Firebase, it's important to understand that the methods are asynchronous and they return Promises. After calling a method, you can use .then() to run code once the Promise is resolved.

auth.signInWithEmailAndPassword(email, password).then((user) => { 
    // You can manipulate the 'user' object here
    if(!errorOccurred) handleSuccess();
}).catch(function(error) {
    errorOccurred = true;
    console.log(errorOccurred);
    var errorCode = error.code;
    var errorMessage = error.message;
    $('#login-error').text(errorMessage);
});

Sometimes, you may not need to explicitly check for errors like in the example above.

For more information, you can visit: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then

In certain situations, you can also provide a second function to the then() method to handle errors when the Promise is rejected. However, for Firebase, error handling is typically done using the catch() method as recommended by the API.

Answer 2

When working with Firebase, it's important to understand that the methods are asynchronous and they return Promises. After calling a method, you can use .then() to run code once the Promise is resolved.

auth.signInWithEmailAndPassword(email, password).then((user) => { 
    // You can manipulate the 'user' object here
    if(!errorOccurred) handleSuccess();
}).catch(function(error) {
    errorOccurred = true;
    console.log(errorOccurred);
    var errorCode = error.code;
    var errorMessage = error.message;
    $('#login-error').text(errorMessage);
});

Sometimes, you may not need to explicitly check for errors like in the example above.

For more information, you can visit: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then

In certain situations, you can also provide a second function to the then() method to handle errors when the Promise is rejected. However, for Firebase, error handling is typically done using the catch() method as recommended by the API.

Executing JavaScript code sequentially

Answer №1

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