How to make a page redirect using JavaScript? [duplicate]

Use:

window.location = "http://my.url.here";

Here’s some quick-n-dirty code that uses jQuery to do what you want. I highly recommend using jQuery. It’ll make things a lot more easier for you, especially since you’re new to JavaScript.

<select id = "pricingOptions" name = "pricingOptions">
    <option value = "500">Option A</option>
    <option value = "1000">Option B</option>
</select>

<script type = "text/javascript" language = "javascript">
    jQuery(document).ready(function() {
        jQuery("#pricingOptions").change(function() {
            if(this.options[this.selectedIndex].value == "500") {
                window.location = "http://example.com/foo.php?option=500";
            }
        });
    });
</script>