javascript框不显示 - 值

Question

我希望我的负面人物不应该显示时，用户单击按钮。计数应该以0结束。 它现在也显示-1，-2，-3个字符。我想只显示0或大于0

<script type="text/javascript" >         
      function plus(){ 
       var addplus = 1; 
       var plus = document.getElementById('qty').value; 
       addplus = parseInt(addplus) + parseInt(plus); 
       document.getElementById('qty').value = addplus; 
      } 
      function negtive(){ 
       var neg; 
       var negtive = 1; 
       var negtives = document.getElementById('qty').value; 
       negtive = parseInt(negtives) - parseInt(negtive);    
       document.getElementById('qty').value = negtive;    
      } 
     </script> 

Answer 1

把这一行

if(negtive<0) 
    negtive = 0; 

后

negtive = parseInt(negtives) - parseInt(negtive); 

OR

document.getElementById('qty').value = ((negtive <0)?0:negtive);