4 Pr0nt0

function testit(string,thing){
    split = string.slice(1).split('&')
    for (var i=0; i<split.length;i++){
        item = split[i]
        item = item.split('=')
        key = item[0]
        value = item[1]
        if (key == thing){
            return value;
        }
    }
}

value = testit(location.search,parameter)
document.write("<img src="+"value+">")