How to get select value for AJAX using JavaScript

Question

I have 2 HTML drop down menus.

<div class="bar-option">
    <label>Filter:</label>
    <form>
        <select name="retreat_locations" onchange="filterRetreats(this.value, 'count(reviews.retreat_id)')">
            <option value="alllocations" selected="selected">All Locations</option>
            <?php foreach ($this->locations as $location) {?>
            <option value="<?=htmlentities($location->retreat_location);?>">
                <?=htmlentities($location->retreat_location);?> </option>
            <?php }?>
        </select>
    </form>
</div>
<div class="bar-option">
    <label>Sort by:</label>
    <select onchange="filterRetreats('alllocations', this.value)">
        <option selected='selected' value='retreat_number_of_reviews'>Popularity</option>
        <option value='retreat_founded_in'>Age</option>
        <option value='total_review_cost'>Cost</option>
    </select>
</div>

As you can see from the above, the second select uses the static value 'alllocations' as the first parameter for the onchange function.

How can I replace this static value with the selected option of the first dropdown (retreat_locations)?

I tried retreat_locations.value but it didn't work.

Any help appreciated.

Answer 1

You can use:

document.querySelector('[name=retreat_locations]').value

Your code will become:

filterRetreats(document.querySelector('[name=retreat_locations]').value, this.value)

Demo:

 function filterRetreats(value1, value2) { console.log(value1, value2); } 

 <div class="bar-option"> <label>Filter:</label> <form> <select name="retreat_locations" onchange="filterRetreats(this.value, 'count(reviews.retreat_id)')"> <option value="alllocations" selected="selected">All Locations</option> <option value="2">2</option> </select> </form> </div> <div class="bar-option"> <label>Sort by:</label> <select onchange="filterRetreats(document.querySelector('[name=retreat_locations]').value, this.value)"> <option selected='selected' value='retreat_number_of_reviews'>Popularity</option> <option value='retreat_founded_in'>Age</option> <option value='total_review_cost'>Cost</option> </select> </div> 

Other -old school- option is to add an id tag to the first select, eg id="retreat_locations" and use document.getElementById('retreat_locations').value .