How to pass parameters on onChange of html select

I am a novice at JavaScript and jQuery. I want to show one combobox-A, which is an HTML <select> with its selected id and contents at the other place on onChange().

How can I pass the complete combobox with its select id, and how can I pass other parameters on fire of the onChange event?

function getComboA(selectObject) {
  var value = selectObject.value;  
  console.log(value);
}

<select id="comboA" onchange="getComboA(this)">
  <option value="">Select combo</option>
  <option value="Value1">Text1</option>
  <option value="Value2">Text2</option>
  <option value="Value3">Text3</option>
</select>

The above example gets you the selected value of combo box on OnChange event.

Another approach wich can be handy in some situations, is passing the value of the selected <option /> directly to the function like this:

function myFunction(chosen) {
  console.log(chosen);
}

<select onChange="myFunction(this.options[this.selectedIndex].value)">
  <option value="1">Text 1</option>
  <option value="2">Text 2</option>
</select>

For how to do it in jQuery:

<select id="yourid">
<option value="Value 1">Text 1</option>
<option value="Value 2">Text 2</option>
</select>

<script src="jquery.js"></script>
<script>
$('#yourid').change(function() {
  alert('The option with value ' + $(this).val() + ' and text ' + $(this).text() + ' was selected.');
});
</script>

You should also know that Javascript and jQuery are not identical. jQuery is valid JavaScript code, but not all JavaScript is jQuery. You should look up the differences and make sure you are using the appropriate one.

JavaScript Solution

<select id="comboA">
<option value="">Select combo</option>
<option value="Value1">Text1</option>
<option value="Value2">Text2</option>
<option value="Value3">Text3</option>
</select>

<script>
 document.getElementById("comboA").onchange = function(){
    var value = document.getElementById("comboA").value;
 };
</script>

or

<script>
 document.getElementById("comboA").onchange = function(evt){
    var value = evt.target.value;
 };
</script>

or

<script>
 document.getElementById("comboA").onchange = handleChange;

 function handleChange(evt){
    var value = evt.target.value;
 };
</script>