JavaScript DOM问题

Question

I want to grab value of selectbox with id "rankono" in var h1 and then below that change my iframe src with parts of h1. If you see the code I've tried to describe what I'm looking for.

Here is the code I've tried

<script>
 var classNumber = document.getElementById('rankdos'); //RANK BILDE 1
classNumber.onchange = runBackgroundChangeDos;

function runBackgroundChangeDos(first){
    var value = first.srcElement.options[first.srcElement.selectedIndex].value;
var h1 = //HERE I LOOOKING FOR WHAT TO TYPE TO GET VALUE OF SELECT WHIT ID rankono
    if (value == 0) {
        document.getElementById('rankimgdos').style.backgroundImage="url('http://localhost/36h8f93.png')"; 
        document.getElementById("PriceFrame").src = "http://www.nordicelite.net/testing/payment.php?crank="h1"&drank=0"; //here i need h1 to show value of select whit id rankono
    } else {
        document.getElementById('rankimgdos').style.backgroundImage="url('http://localhost/rgeg.png')";
    document.getElementById("rankto").innerHTML = "None";
    };
}
</script>

Answer 1

First grab the value

var h1 = document.getElementById('rankono').value;

then use it like below:

document.getElementById("PriceFrame").src = "http://www.nordicelite.net/testing/payment.php?crank=" + h1 + "&drank=0";

If you want to concatenate a string with a variable in JS, use

var variable = 'bar';
var str = 'Foo' + variable + 'baz';
console.log(str) // Foobarbaz

---

If your browser supports ES-2015 features, you may use template strings:

var variable = 'bar';
var str = `Foo${variable}baz`;
console.log(str); // Foobarbaz