Utilizing Javascript to Generate a Comma-Separated List from Multiple Select Elements

Question

Utilizing Javascript to Generate a Comma-Separated List from Multiple Select Elements

I have a set of dynamic single-option select elements that I need to work with. My goal is to generate a list containing the indexes of all selected options, separated by commas. Currently, I am using

elements = document.getElementsByClassName("my-class");

This code snippet retrieves a node list (which I assume functions like an array) of all select elements, and while I am aware of .selectedIndex, I'm unsure of how to proceed from there.

The desired output format is:

3,4,6,1

I intend to utilize this data in a query string for some specific operations.

Any assistance on this matter would be greatly appreciated.

var counter = 1;
function addInput(divName){
var newdiv = document.createElement('div');
var counterid = counter;
var newdivid = "dynamic-div-"+counterid;
newdiv.setAttribute("id", newdivid);
oldelement = document.getElementById('cat-drop-id');
newelement = oldelement.cloneNode(true);
newdiv.innerHTML = "<br><select name='cat' id='cat-dropdown-id" + counterid + "' class='som-changecat-category-dropdown'>" + newelement.innerHTML + "</select><input type='button' id='remove-button-id" + counterid + "' value='Remove DUMMY' onclick='removeDummy(this.id);' /><br><br>";

document.getElementById(divName).appendChild(newdiv);
counter++;
}

function removeDummy(elementtoremove) {
var elem = document.getElementById(elementtoremove);
elem.parentNode.parentNode.removeChild(elem.parentNode);
return false;
}

<form action="?page=test-options-page&something=0" method="POST">
<div id="dynamicInput">
<select name="cat" id="cat-drop-id" class="som-changecat-category-dropdown">
<option value="-1">Select category</option>
<option class="level-0" value="1">test</option>
<option class="level-0" value="2">test2</option>
</select>
</div>
<input type="button" value="Add another dropdown" onClick="addInput('dynamicInput');">
<input type="submit" value="Submit">
</form>

javascript

Answer 1

Answer №1

To successfully convert a nodeList to an array, you just need to follow a simple process. For more detailed information on this topic, you can refer to this helpful guide: https://davidwalsh.name/nodelist-array

Below is the complete code snippet that demonstrates this conversion:

Pay attention to the additional button I included and the getValue() method as well =)

<form action="?page=test-options-page&something=0" method="POST">
  <div id="dynamicInput">
    <select name="cat" id="cat-drop-id" class="som-changecat-category-dropdown">
      <option value="-1">Select category</option>
      <option class="level-0" value="1">test</option>
      <option class="level-0" value="2">test2</option>
    </select>
  </div>
  <input type="button" value="Add another dropdown" onClick="addInput('dynamicInput');">
  <input type="submit" value="Submit">
  <button onClick="getValue(event)">get comma separated value</button>
</form>

<script>

  var counter = 1;
  function addInput(divName){
    var newdiv = document.createElement('div');
    var counterid = counter;
    var newdivid = "dynamic-div-"+counterid;
    newdiv.setAttribute("id", newdivid);
    oldelement = document.getElementById('cat-drop-id');
    newelement = oldelement.cloneNode(true);
    newdiv.innerHTML = "<br><select name='cat' id='cat-dropdown-id" + counterid + "' class='som-changecat-category-dropdown'>" + newelement.innerHTML + "</select><input type='button' id='remove-button-id" + counterid + "' value='Remove DUMMY' onclick='removeDummy(this.id);' /><br><br>";

    document.getElementById(divName).appendChild(newdiv);
    counter++;
  }

function removeDummy(elementtoremove) {
  var elem = document.getElementById(elementtoremove);
  elem.parentNode.parentNode.removeChild(elem.parentNode);
  return false;
}

function getValue(event) {
  event.preventDefault();

  // obtain all select elements
  var selects = document.getElementById('dynamicInput').querySelectorAll('select');

  // transforming nodeList into an array
  var selectsArray = Array.prototype.slice.call(selects)

  // now you can utilize Array.prototype.*
  var result = selectsArray.map(select => {
    return select.value;
  }).join(',');

  // further actions with 'result'
  console.log(result);

  return result;
}


</script>

Answer 2

To successfully convert a nodeList to an array, you just need to follow a simple process. For more detailed information on this topic, you can refer to this helpful guide: https://davidwalsh.name/nodelist-array

Below is the complete code snippet that demonstrates this conversion:

Pay attention to the additional button I included and the getValue() method as well =)

<form action="?page=test-options-page&something=0" method="POST">
  <div id="dynamicInput">
    <select name="cat" id="cat-drop-id" class="som-changecat-category-dropdown">
      <option value="-1">Select category</option>
      <option class="level-0" value="1">test</option>
      <option class="level-0" value="2">test2</option>
    </select>
  </div>
  <input type="button" value="Add another dropdown" onClick="addInput('dynamicInput');">
  <input type="submit" value="Submit">
  <button onClick="getValue(event)">get comma separated value</button>
</form>

<script>

  var counter = 1;
  function addInput(divName){
    var newdiv = document.createElement('div');
    var counterid = counter;
    var newdivid = "dynamic-div-"+counterid;
    newdiv.setAttribute("id", newdivid);
    oldelement = document.getElementById('cat-drop-id');
    newelement = oldelement.cloneNode(true);
    newdiv.innerHTML = "<br><select name='cat' id='cat-dropdown-id" + counterid + "' class='som-changecat-category-dropdown'>" + newelement.innerHTML + "</select><input type='button' id='remove-button-id" + counterid + "' value='Remove DUMMY' onclick='removeDummy(this.id);' /><br><br>";

    document.getElementById(divName).appendChild(newdiv);
    counter++;
  }

function removeDummy(elementtoremove) {
  var elem = document.getElementById(elementtoremove);
  elem.parentNode.parentNode.removeChild(elem.parentNode);
  return false;
}

function getValue(event) {
  event.preventDefault();

  // obtain all select elements
  var selects = document.getElementById('dynamicInput').querySelectorAll('select');

  // transforming nodeList into an array
  var selectsArray = Array.prototype.slice.call(selects)

  // now you can utilize Array.prototype.*
  var result = selectsArray.map(select => {
    return select.value;
  }).join(',');

  // further actions with 'result'
  console.log(result);

  return result;
}


</script>

Answer 3

Answer №2

Since using .selectedOptions isn't entirely safe, the best approach is to iterate through each select option and retrieve the selected ones. You can try something like this:

var selects = document.getElementsByClassName('som-changecat-category-dropdown');
var values = {}, select, id, optionValues;
for (var i = 0; i < selects.length; i++) {
  select = selects[i];
  id = select.id;
  optionValues = [];
  for (var j = 0; j < select.options.length; j++) {  
    var option = select.options[j];
    if (option.selected) optionValues.push(option.value);
  }
  values[select.id] = optionValues.join(',');
}
// This code gives you an object with the selects’ ids as keys 
// and the comma-separated values as value
document.write(JSON.stringify(values));

<form action="?page=test-options-page&something=0" method="POST">
<div id="dynamicInput">
    <select multiple id="cat-dropdown-1" class="som-changecat-category-dropdown">
     <option value="1" selected>bli</option>
     <option value="2">bla</option>
     <option value="3" selected>blu</option>
    </select>
    <select multiple id="cat-dropdown-2" class="som-changecat-category-dropdown">
     <option value="4">blimm</option>
     <option value="5" selected>blamm</option>
     <option value="6" selected>blumm</option>
    </select>
</div>
<input type="button" value="Add another dropdown" onClick="addInput('dynamicInput');">
<input type="submit" value="Submit">
</form>

This method allows you to gather all form elements' values and utilize the resulting object to construct your query string.

Answer 4

Since using .selectedOptions isn't entirely safe, the best approach is to iterate through each select option and retrieve the selected ones. You can try something like this:

var selects = document.getElementsByClassName('som-changecat-category-dropdown');
var values = {}, select, id, optionValues;
for (var i = 0; i < selects.length; i++) {
  select = selects[i];
  id = select.id;
  optionValues = [];
  for (var j = 0; j < select.options.length; j++) {  
    var option = select.options[j];
    if (option.selected) optionValues.push(option.value);
  }
  values[select.id] = optionValues.join(',');
}
// This code gives you an object with the selects’ ids as keys 
// and the comma-separated values as value
document.write(JSON.stringify(values));

<form action="?page=test-options-page&something=0" method="POST">
<div id="dynamicInput">
    <select multiple id="cat-dropdown-1" class="som-changecat-category-dropdown">
     <option value="1" selected>bli</option>
     <option value="2">bla</option>
     <option value="3" selected>blu</option>
    </select>
    <select multiple id="cat-dropdown-2" class="som-changecat-category-dropdown">
     <option value="4">blimm</option>
     <option value="5" selected>blamm</option>
     <option value="6" selected>blumm</option>
    </select>
</div>
<input type="button" value="Add another dropdown" onClick="addInput('dynamicInput');">
<input type="submit" value="Submit">
</form>

This method allows you to gather all form elements' values and utilize the resulting object to construct your query string.

Utilizing Javascript to Generate a Comma-Separated List from Multiple Select Elements

Answer №1

Answer №2

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