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Tolerim
a month ago

How can I manage events that occur with the TAB key or when the input field is altered using "onchange"?

As a JavaScript developer, I am tasked with finding a way to handle a "change" event on an input field, which triggers an Ajax request. If the request returns an error, it is displayed at the top of the page. However, if the user presses the "TAB" key, the cursor moves to the next field before the "change" event can fire, causing the error message to be displayed offscreen. Is there another approach to handling this issue, or should I consider using a different event such as "keydown"?
Answers(2)
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Vogi
a month ago
Verified Answer
One approach to this issue is to delay the Ajax request until the user has stopped typing. This can be done by setting a timer that waits for a certain amount of time after the last keystroke before sending the request. Here is an example of how this can be done in jQuery: 
var changeTimer = false;
$('input').on('change', function() {
    if (changeTimer !== false) clearTimeout(changeTimer);
    changeTimer = setTimeout(function() {
        /* your ajax here */
        changeTimer = false;
    }, 300);
});
This code sets a timer for 300 milliseconds after the last keystroke before sending the Ajax request. This should give the user enough time to press the "TAB" key before the request is sent. Another approach is to use the "keydown" event instead of the "change" event. The "keydown" event fires when a key is pressed down, so it will fire before the "TAB" key moves focus to the next field. However, this approach has its own drawbacks, such as firing multiple times if the user holds down a key. I hope this helps! Let me know if you have any other questions.

Sources

Handling Multiple Inputs with a Single onChange Handler in ReactHow do you send an ajax request every time that a form input field changes?How to handle events with TAB key and "onchange" on input field
avatar
Tolerim
a month ago
One way to deal with this issue is to prevent the default behavior of the "TAB" key and manually trigger the "change" event on the input field before allowing the focus to move to the next input field. This can be done using the preventDefault() method and the trigger() method from jQuery. Here is an example of how you can implement this solution: 
$('#input-field').on('keydown', function(event) {
  if (event.keyCode === 9) {
    event.preventDefault();
    $(this).trigger('change');
    $(this).next().focus();
  }
});

$('#input-field').on('change', function() {
  $.ajax({
    url: 'your-url',
    success: function(data) {
      // handle success response
    },
    error: function(error) {
      $('#error-message').html(error.responseText);
      $('html, body').animate({scrollTop: 0}, 'slow');
    }
  });
});
In this example, we are listening to the "keydown" event on the input field and checking if the keyCode is equal to 9 (which is the keyCode for the TAB key). If it is, we prevent the default behavior of the keypress, trigger the "change" event on the input field, and then move the focus to the next input field using the next() method from jQuery. We also have an event listener for the "change" event on the input field, which will dispatch the ajax request and handle the success or error response. In the error response, we are injecting the error message on the html and using the scrollTop() method from jQuery to scroll to the top of the page where the error message is displayed.
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