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Jquery – Can I override the onChange trigger of a selectize input?

I have a selectize input and want to change its behaviour. I normally use selectize inputs from within some framework (shiny), so I hope the example that I give here is understandable and precise.

I want to change the logic, when an onChange – event is triggered. I only want this to happen when there is one element selected, not when none is selected. In case the user deletes the element and leaves the form untouched, I want to restore the value that was active before.

Have a look at the following code:

$(document).ready(function() {
  var selectize = $('#select-beast').selectize({
    delimiter: ',',
    persist: false,
    create: function(input) {
      return {
        value: input,
        text: input
      }
    }
  });

  selectize[0].selectize.on('change', function() {
    var value = selectize[0].selectize.getValue();
    console.log(value);
  });
});
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Selectize Example</title>
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/selectize.js/0.13.3/css/selectize.default.min.css">
</head>
<body>
  <select id="select-beast" multiple placeholder="Select a beast...">
    <option value="lion">Lion</option>
    <option value="tiger">Tiger</option>
    <option value="bear">Bear</option>
    <option value="elephant">Elephant</option>
    <option value="rhino">Rhino</option>
  </select>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/selectize.js/0.13.3/js/standalone/selectize.min.js"></script>
</body>
</html>

So in my case the log message should only ever print out something like Array["bear"] but never an empty array. I know that in this case one could do a if before the console.log but I am explicitly asking for changing the onChange condition because in my real problem I have no direct control on what my framework is doing. Is there a way of achieving my goal?

  • no change-event with empty selection
  • restoring the value that was there before, once the user gives focus to another element

I would claim that it is pretty natural to want something like that, so maybe there is even a plugin capable of achieving my goals?

Tags:

2

Answers


  1. 0

    We can’t override the code but we can get around it. I got around it by pushing value into an array and then logging the first last (confusing I know) selected value instead of an empty array. There was a few issues I fixed with little bits and bobs but I’ve commented them out for you.

    Please upvote or comment if this helps. Accepting the answer would be nice too.

    $(document).ready(function() {
  let selectize = $('#select-beast').selectize({
    delimiter: ',',
    persist: false,
    create: function(input) {
      return {
        value: input,
        text: input
      }
    }
  });

let previousLog = [];
  selectize[0].selectize.on('change', function() {
    let value = selectize[0].selectize.getValue();

    previousLog.push("" + value); //IDK why but the empty string + value is just what makes this work so I'm going to point this towards js behaviour
    let lastLogged = previousLog.length - 2; //Getting last selected first value. I minus 2 to not log the empty string aswell as other values.

    if(value.length == 0){
      console.log([previousLog[lastLogged]]) //Logging as array rather than string.
    } else {
        console.log(value); //Normal value log
    }
  });
});
    <!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Selectize Example</title>
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/selectize.js/0.13.3/css/selectize.default.min.css">
</head>
<body>
  <select id="select-beast" multiple placeholder="Select a beast...">
    <option value="lion">Lion</option>
    <option value="tiger">Tiger</option>
    <option value="bear">Bear</option>
    <option value="elephant">Elephant</option>
    <option value="rhino">Rhino</option>
  </select>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/selectize.js/0.13.3/js/standalone/selectize.min.js"></script>
</body>
</html>

    Upvote if this helps!

    Login or Signup to reply.
  2. 0

    I don’t quite understand what you want.
    But you can override the change event and not call your function if value.length === 0 (this will work with <select multiple> and without multiple).
    It’s a bit dirty:

    const selectize = $('#select-beast').selectize({
  delimiter: ',',
  persist: false,
  create: function(input) {
    return {
      value: input,
      text: input
    }
  }
});

/* We save the event */
const originalOnChange = selectize[0].selectize._events.change; 

selectize[0].selectize.on('change', function() {
  var value = selectize[0].selectize.getValue();
  console.log(value);
});

/* We turn off the event */
selectize[0].selectize.off('change');

selectize[0].selectize._events.change = [];
selectize[0].selectize._events.change[0] = function(value) {
  /* If is no value - we do nothing */
  if(!value.length){
    return;
  }
  /* Or call previously saved functions */
  originalOnChange[0].call(this);
  originalOnChange[1]();
}
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/selectize.js/0.13.3/css/selectize.default.min.css">
<select id="select-beast" multiple placeholder="Select a beast...">
  <option value="lion">Lion</option>
  <option value="tiger">Tiger</option>
  <option value="bear">Bear</option>
  <option value="elephant">Elephant</option>
  <option value="rhino">Rhino</option>
</select>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/selectize.js/0.13.3/js/standalone/selectize.min.js"></script>
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