Javascript verify integer or float value from textbox

// vaild inter number function
 1 function isInteger(obj, Name)
 2             {
 3                 if( obj.value == "" )
 4                     return true;
 5     
 6                 var regu = /^[-]{0,1}[0-9]{1,}$/;
 7                 if( isNaN(obj.value) || !regu.test(obj.value))
 8                 {
 9                     alert(Name + ' must be integral number!');
10                     obj.focus();
11                     return false;
12                 }
13                 
14                 return true;
15             }

 1 // verify float number from textbox
 2  function ChangeQTY(obj, Name)
 3             {    
 4                 
 5                 if (obj.value != "" && isNaN(obj.value))
 6                 {
 7                     alert(Name + ' must be number!');
 8                     obj.focus();
 9                     return false;
10                 }
11             }