Use checkbox to choose which array(s) to select a random value from in JavaScript

In the fiddle:

Two random selections (one from each array) are given on clicking the Go button.

My question:

I would like to use checkboxes (or similar) to determine which value should be randomised and which should be 'saved'.

Example:

• Click Go
• '2' & '6' are given
• Tick a checkbox under '2' to 'save' the value
• Click Go again
• 2 remains, second value is now 4

http://ift.tt/2vujjJI

HTML:

<input class="btn" type="button" id="btnSearch" value="Go" onclick="GetValue();" />
<p id="message1" >Random</p>
<p id="message2" >Random</p>

JS:

function GetValue()
{
var myarray1 = new Array("1","2","3");
var myarray2 = new Array("4","5","6");
var random1 = myarray1[Math.floor(Math.random() * myarray1.length)];
var random2 = myarray2[Math.floor(Math.random() * myarray2.length)];
document.getElementById("message1").innerHTML=random1;
document.getElementById("message2").innerHTML=random2;
}

The example is completely stripped back for simplicity; I would be using it on a larger scale.

Any help on this would be greatly appreciated! Thanks in advance.