用js计算人体胖瘦

    <script type="text/javascript">
        var weight=prompt("请输入你体重(公斤)~");
        var height=prompt("请输入你的身高(米)~");
        getLast(weight,height);
        function getLast(weight,height){
            setTimeout(function(){
                var last=weight/(height*height);
                function getOkValue(last){
                    var weightOk;
                    var heightOk;
                    if(last <18){
                        
                        weightOk=18*height*height;
                        heightOk=Math.sqrt(weight/18) ;
                        
                    }else if(last>25){
                        weightOk=25*height*height;
                        weightOk=weight/25;
                    }
                    return "休重应增加"+(weightOk-weight)+"kg,或身高"+(heightOk-height)+"m方可回到正常值。"
                    
                }
                if(last>=18 && last<=25){
                    alert("BMI值是"+last+",正常~");
                }else if(last<18){
                    alert("BMI值是"+last+","+getOkValue(last)+"偏瘦呢，亲~");
                }else if(last>25){
                    alert("BMI值是"+last+","+getOkValue(last)+"偏胖呢，亲~");
                }
            },1000);
            
            
        }
            
           
    
    </script>