javascript - how to get a URL parameter and set the value of a select option on page load?

I'm new to Javascript and I can't find a simple example of this online.

I have a simple HTML page with a select widget on it:

<select name="myProduct">
    <option value="aaa">This is AAA</option>
    <option value="bbb">This is BBB</option>
    <option value="ccc">This is CCC</option>
</select>

What's an easy way to pass a param to the URL like so ...

/mypage.html?selectedProduct=CCC

... and have the value selected in the widget on page load?

I'm new to Javascript and I can't find a simple example of this online.

I have a simple HTML page with a select widget on it:

<select name="myProduct">
    <option value="aaa">This is AAA</option>
    <option value="bbb">This is BBB</option>
    <option value="ccc">This is CCC</option>
</select>

What's an easy way to pass a param to the URL like so ...

/mypage.html?selectedProduct=CCC

... and have the value selected in the widget on page load?

Share Improve this question asked Jul 16, 2020 at 18:41 AndySummers2020 4511 gold badge8 silver badges16 bronze badges

You can use: window.location.search.split("=")[1] that will return, in your example, CCC. Then: document.getElementById("myProduct") (you'll have to add id, or use document.getElementsByName("myProduct")[0] - if you only have one), then iterate over the options, pare value to lowerCase of CCC and set selected. you'd have to do more work on window.location.search if you're passing more var/val pairs. Oh, and what to do if nothing/different var... – iAmOren Commented Jul 16, 2020 at 19:06
document.getElementsByName("myProduct")[0] is a very bad idea. – Scott Marcus Commented Jul 16, 2020 at 19:07
@ScottMarcus, I know - it's better to use id instead of name - just went with the data provided. Your answer, with var urlParams = new URLSearchParams(window.location.search); let queryString = urlParams.get('selectedProduct'); is very good! – iAmOren Commented Jul 16, 2020 at 19:10
@ScottMarcus, that's why I didn't write that as an answer... – iAmOren Commented Jul 16, 2020 at 19:10
@iAmOren Actually, it's better not to use ID at all as ID's make code brittle and don't scale. With the code provided, you could/should use .querySelector() (as I indicate in my link). – Scott Marcus Commented Jul 16, 2020 at 19:11

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2 Answers 2

Sorted by: Reset to default 5

Set up a change event handler on the select and append the querystring (that has the value of the select concatenated on to it) to the current URL.

var urlParams = new URLSearchParams(window.location.search);
let queryString = urlParams.get('selectedProduct');

// Find the option in the select that has the same value as
// the query string value and make it be selected
document.getElementById("myProduct").querySelector("option[value='" + queryString + "']").selected = true;

<select id="myProduct">
    <option value="aaa">This is AAA</option>
    <option value="bbb">This is BBB</option>
    <option value="ccc">This is CCC</option>
</select>

I got it working like so ...

<html>

<head>
/* .... */
<script src="https://ajax.googleapis./ajax/libs/jquery/3.5.1/jquery.min.js"></script>
</head>

<script type="text/javascript">
    $(function() {
        var selectedProduct = GetURLParameter("selectedProduct");
        if (selectedProduct) {
            $("#myProduct").val(selectedProduct); 
        }
    });
    
    function GetURLParameter(sParam)
    {
        var sPageURL = window.location.search.substring(1);
        var sURLVariables = sPageURL.split('&');
        for (var i = 0; i < sURLVariables.length; i++)
        {
            var sParameterName = sURLVariables[i].split('=');
            if (sParameterName[0] == sParam)
            {
                return sParameterName[1];
            }
        }
    }
</script>

<body>

<select id="myProduct"> <!-- NOTE that's 'id', not 'name' there -->
    <option value="aaa">This is AAA</option>
    <option value="bbb">This is BBB</option>
    <option value="ccc">This is CCC</option>
</select>

</body

</html>

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javascript - how to get a URL parameter and set the value of a select option on page load? - Stack Overflow

2 Answers 2