在更改时从 Select 获取选定的值/文本

Question

<select onchange="test()" id="select_id">
    <option value="0">-Select-</option>
    <option value="1">Communication</option>
</select>

I need to get the value of the selected option in javascript: does anyone know how to get the selected value or text, please tell how to write a function for it. I have assigned onchange() function to select so what do i do after that?

Answer 1

Use either JavaScript or jQuery for this.

Using JavaScript

<script>
function val() {
    d = document.getElementById("select_id").value;
    alert(d);
}
</script>

<select onchange="val()" id="select_id">

Using jQuery

$('#select_id').change(function(){
    alert($(this).val());
})

Answer 2

If you're googling this, and don't want the event listener to be an attribute, use:

 document.getElementById('my-select').addEventListener('change', function() { console.log('You selected: ', this.value); });

 <select id="my-select"> <option value="1">One</option> <option value="2">Two</option> <option value="3">Three</option> </select>

Answer 3

Wow, no really reusable solutions among answers yet.. I mean, a standart event handler should get only an event argument and doesn't have to use ids at all.. I'd use:

function handleSelectChange(event) {

    // if you want to support some really old IEs, add
    // event = event || window.event;

    var selectElement = event.target;

    var value = selectElement.value;
    // to support really old browsers, you may use
    // selectElement.value || selectElement.options[selectElement.selectedIndex].value;
    // like el Dude has suggested

    // do whatever you want with value
}

You may use this handler with each – inline js:

<select onchange="handleSelectChange(event)">
    <option value="1">one</option>
    <option value="2">two</option>
</select>

jQuery:

jQuery('#select_id').on('change',handleSelectChange);

or vanilla JS handler setting:

var selector = document.getElementById("select_id");
selector.onchange = handleSelectChange;
// or
selector.addEventListener('change', handleSelectChange);

And don't have to rewrite this for each select element you have.

Example snippet:

 function handleSelectChange(event) { var selectElement = event.target; var value = selectElement.value; alert(value); }

 <select onchange="handleSelectChange(event)"> <option value="1">one</option> <option value="2">two</option> </select>

Answer 4

 function test(a) { var x = (a.value || a.options[a.selectedIndex].value); //crossbrowser solution =) alert(x); }

 <select onchange="test(this)" id="select_id"> <option value="0">-Select-</option> <option value="1">Communication</option> <option value="2">Communication</option> <option value="3">Communication</option> </select>

Answer 5

No need for an onchange function. You can grab the value in one line:

document.getElementById("select_id").options[document.getElementById("select_id").selectedIndex].value;

Or, split it up for better readability:

var select_id = document.getElementById("select_id");

select_id.options[select_id.selectedIndex].value;

Answer 6

let dropdown = document.querySelector('select');
if (dropdown) dropdown.addEventListener('change', function(event) {
    console.log(event.target.value);
});

Answer 7

I wonder that everyone has posted about value and text option to get from <option> and no one suggested label .

So I am suggesting label too, as supported by all browsers

To get value (same as others suggested)

function test(a) {
var x = a.options[a.selectedIndex].value;
alert(x);
}

To get option text (ie Communication or -Select-)

function test(a) {
var x = a.options[a.selectedIndex].text;
alert(x);
}

OR (New suggestion)

function test(a) {
var x = a.options[a.selectedIndex].label;
alert(x);
}

HTML

<select onchange="test(this)" id="select_id">
    <option value="0">-Select-</option>
    <option value="1">Communication</option>
    <option value="2" label=‘newText’>Communication</option>
</select>

Note: In above HTML for option value 2, label will return newText instead of Communication

Also

Note: It is not possible to set the label property in Firefox (only return).

Answer 8

HTML:

<select onchange="cityChanged(this.value)">
      <option value="CHICAGO">Chicago</option>
      <option value="NEWYORK">New York</option>
</select>

JS:

function cityChanged(city) {
    alert(city);
}

Answer 9

Use

document.getElementById("select_id").selectedIndex

Or to get the value:

document.getElementById("select_id").value

Answer 10

<script>
function test(a) {
    var x = a.selectedIndex;
    alert(x);
}
</script>
<select onchange="test(this)" id="select_id">
    <option value="0">-Select-</option>
    <option value="1">Communication</option>
    <option value="2">Communication</option>
    <option value="3">Communication</option>
</select>

in the alert you'll see the INT value of the selected index, treat the selection as an array and you'll get the value

Answer 11

Why overcomplicate it:

var select = document.querySelector('[select#id.orClass]');
select.addEventListener('change', function() {
  console.log(select.value);

  // or if it changes dynamically
  console.log(e.target.value);      
});

 let select = document.getElementById('select_id'); select.addEventListener('change', function() { console.log(select.value); // just for test alert(select.value); });

 <select id="select_id"> <option value="0">-Select-</option> <option value="1">Communication</option> </select>

Answer 12

 $('#select_id').change(function(){ // selected value alert($(this).val()); // selected text alert($(this).find("option:selected").text()); })

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.0/jquery.min.js"></script> <select onchange="test()" id="select_id"> <option value="0">-Select-</option> <option value="1">Communication</option> </select>

Answer 13

This is an old question, but I am not sure why people didn't suggest using the event object to retrieve the info instead of searching through the DOM again.

Simply go through the event object in your function onChange, see example bellow

function test() { console.log(event.srcElement.value); }

http://jsfiddle.net/Corsico/3yvh9wc6/5/

Might be useful to people looking this up today if this wasn't default behavior 7 years ago

Answer 14

 function test(){ var sel1 = document.getElementById("select_id"); var strUser1 = sel1.options[sel1.selectedIndex].value; console.log(strUser1); alert(strUser1); // Inorder to get the Test as value ie "Communication" var sel2 = document.getElementById("select_id"); var strUser2 = sel2.options[sel2.selectedIndex].text; console.log(strUser2); alert(strUser2); }

 <select onchange="test()" id="select_id"> <option value="0">-Select-</option> <option value="1">Communication</option> </select>

Answer 15

 function test(){ var sel1 = document.getElementById("select_id"); var strUser1 = sel1.options[sel1.selectedIndex].value; console.log(strUser1); alert(strUser1); // Inorder to get the Test as value ie "Communication" var sel2 = document.getElementById("select_id"); var strUser2 = sel2.options[sel2.selectedIndex].text; console.log(strUser2); alert(strUser2); }

 <select onchange="test()" id="select_id"> <option value="0">-Select-</option> <option value="1">Communication</option> </select>

var e = document.getElementById("ddlViewBy");
var strUser = e.options[e.selectedIndex].value;

Answer 16

I have tried to explain with my own sample, but I hope it will help you. You don't need onchange="test()" Please run code snippet for getting a live result.

 document.getElementById("cars").addEventListener("change", displayCar); function displayCar() { var selected_value = document.getElementById("cars").value; alert(selected_value); }

 <select id="cars"> <option value="bmw">BMW</option> <option value="mercedes">Mercedes</option> <option value="volkswagen">Volkswagen</option> <option value="audi">Audi</option> </select>

Answer 17

You can get it just using plain old easy and simple JavaScript .

 <select onchange="test()" id="select_id">
  <option value="0">-Select-</option>
  <option value="1">Communication</option>
 </select>

 function test()
 {
  let order_details_id=document.getElementById('select_id').value;
  alert(select_id);
 }

Answer 18

You can get the value from the select element by passing "this.value" as
a parameter to your function named test(this.value) and after that
You should create the function with a parameter inside the script element
and finally u can write console.log(number) inside this function to get Your selected value.


<!DOCTYPE html>
    <html>
    <body>
    
    <p>Select a new car from the list.</p>
    <select onchange="test(this.value)" id="select_id">
        <option value="0">-Select-</option>
        <option value="1">Communication</option>
    </select>
    
   
    
    <script>
    function test(number){
    console.log(number)
    }
    
    </script>
    
    </body>
    </html>

Answer 19

In html

(change)="onChangeCategory($event)"

In javascript/typescript

onChangeCategory(event: any) {
    console.log(event.target.options[event.target.selectedIndex].value);
    console.log(event.target.options[event.target.selectedIndex].text);
}

Answer 20

You set the onchange handler to some function or string. In it, you write code to get value

document.getElementById('cphForm_ddlFacility').value;

or, for older browsers

document.getElementById('cphForm_ddlFacility')[document.getElementById('cphForm_ddlFacility').selectedIndex].value