How to get all selected values from <select multiple=multiple>?

Question

Unless a question asks for JQuery the question should be first answered in standard javascript as many people do not use JQuery in their sites.

From RobG How to get all selected values of a multiple select box using JavaScript?:

  function getSelectValues(select) {
  var result = [];
  var options = select && select.options;
  var opt;

  for (var i=0, iLen=options.length; i<iLen; i++) {
    opt = options[i];

    if (opt.selected) {
      result.push(opt.value || opt.text);
    }
  }
  return result;
}

The usual way:

var values = $('#select-meal-type').val();

From the docs:

In the case of <select multiple="multiple"> elements, the .val() method returns an array containing each selected option;

Actually, I found the best, most-succinct, fastest, and most-compatible way using pure JavaScript (assuming you don't need to fully support IE lte 8) is the following:

var values = Array.prototype.slice.call(document.querySelectorAll('#select-meal-type option:checked'),0).map(function(v,i,a) { 
    return v.value; 
});

UPDATE (2017-02-14):

An even more succinct way using ES6/ES2015 (for the browsers that support it):

const selected = document.querySelectorAll('#select-meal-type option:checked');
const values = Array.from(selected).map(el => el.value);

If you wanna go the modern way, you can do this:

const selectedOpts = [...field.options].filter(x => x.selected);

The ... operator maps iterable (HTMLOptionsCollection) to the array.

If you're just interested in the values, you can add a map() call:

const selectedValues = [...field.options]
                     .filter(x => x.selected)
                     .map(x => x.value);

You can use selectedOptions property

var options = document.getElementById('select-meal-type').selectedOptions;
var values = Array.from(options).map(({ value }) => value);
console.log(values);

<select id="select-meal-type" multiple="multiple">
    <option value="1">Breakfast</option>
    <option value="2" selected>Lunch</option>
    <option value="3">Dinner</option>
    <option value="4" selected>Snacks</option>
    <option value="5">Dessert</option>
</select>

First, use Array.from to convert the HTMLCollection object to an array.

let selectElement = document.getElementById('categorySelect')
let selectedValues = Array.from(selectElement.selectedOptions)
        .map(option => option.value) // make sure you know what '.map' does

// you could also do: selectElement.options

$('#select-meal-type :selected') will contain an array of all of the selected items.

$('#select-meal-type option:selected').each(function() {
    alert($(this).val());
});

​