JavaScript Setting iframe src as a javascript variable

[fortran_cookie]

Sorry if this is a stupid question- I have a project that displays a site in an iframe based on a text box input. I need some way to set the iframe src as a variable so that the iframe can display multiple sites. However, this does not work, and I've scoured the internet for a solution, and can't find it. Here's my code so far: (x is the variable from the text box)

    <iframe id="linkhere" scrolling="yes" height="350" width ="1509" src=""></iframe>
   
    <script>
        document.getElementById("linkhere").src = x;
    </script>

Thanks.

 

[OldMan]

The easiest way to have an onclick for each (whatever a 'text box input' is) and call the same function and pass the src to that function.

onclick ="controlFrame('google.com')"
and
function controlFrame(thesrc){
    <iframe id="linkhere" scrolling="yes" height="350" width ="1509" src="thesrc"></iframe>
}

 

[fortran_cookie]

Thank you very much! And sorry I used incorrect terminology, I'm new to coding.