function doMap()
{
    var parameter=window.document.getElementById('hidImgValue').value;
    var item=parameter.split('|');
    window.document.getElementById('img_mainMap').src=item[fRandomBy(0,item.length-1)];
}
function fRandomBy(under, over)
{ 
    switch(arguments.length)
    { 
        case 1: return parseInt(Math.random()*under+1); 
        case 2: return parseInt(Math.random()*(over-under+1) + under); 
        default: return 0; 
    } 
} 
doMap();