回答-BFW问答

//生成从minNum到maxNum的随机数
function randomNum(minNum,maxNum){ 
    switch(arguments.length){ 
        case 1: 
            return parseInt(Math.random()*minNum+1,10); 
        break; 
        case 2: 
            return parseInt(Math.random()*(maxNum-minNum+1)+minNum,10); 
        break; 
            default: 
                return 0; 
            break; 
    } 
} 
 alert(randomNum(1,1000));