[面试题] javascript 如何校验数字型？

见过两回了这道题

解决方案 »

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<script>
var a = 111;
alert(typeof(a));
</script>
alert(typeof(xx) == number)这句就可以吧？
//检查输入参数是否全为数字
                  checkNumber                 :function(str){
                                                                  if   (str   ==   null   ||   str   ==   ""){
                                                          return   false;
                                                  }
                                  else   if(str.length==0){
                          return   false;
                                  }
                                  else{
                                          for   (i=0;i<str.length;i++){
                                                  if   (str.charAt(i)<'0'   ||   str.charAt(i)>'9'){
                                                                  return   false;
                                                                  break;
                                                                  }
                                                          }
                                  }
                                                                return   true;
                                                        }


  <SCRIPT   language="JavaScript">
  if(!checkNumber(id1))
  {
  alert("不是数字型!");
  return   false;
  }
  </SCRIPT>
isNaN(argu) //is not a number
如果是数字(不包括float类型数),返回false ,否则true
function checkInteger(s) {
var patrn = /^[+-]?\\d+(.\\d+)?$/;
if (!patrn.exec(s)) {
alert("not integer.");
return false;
}
return true
}
<script>
var a = 123;
alert(typeof(a));
</script>
<script>
var a = 123;
alert(typeof(a));
</script>
我写了一个Demo，很原始，呵呵
<html>
<script language="javascript">
function isNum()
{
var boolean =false;
var number = '0123456789';
var str = document.getElementById('isNum').value;
for(var i=0;i<str.length;i++)
{
var cur = str.charAt(i);
if(number.indexOf(cur) == -1)
{
bo = false;
}else
{
bo = true;
}
}
if(bo)
{
alert('合法字符');
}else
{
alert('非法字符');
}
}
</script>
<body>
<table>
<tr><td>
<input type="type" name="isNum">
<input type="button" value="验证" onclick="isNum()">
</td></tr>
</table>
</body>
</html>
我写了一个Demo，很原始，呵呵
<html>
<script   language= "javascript ">
function   isNum()
{
var   boolean   =false;
var   number   =   '0123456789 ';
var   str   =   document.getElementById( 'isNum ').value;
for(var   i=0;i <str.length;i++)
{
var   cur   =   str.charAt(i);
if(number.indexOf(cur)   ==   -1)
{
bo   =   false;
}else
{
bo   =   true;
}
}
if(bo)
{
alert( '合法字符 ');
}else
{
alert( '非法字符 ');
}
}
</script>
<body>
<table>
<tr> <td>
<input   type= "type "   name= "isNum ">
<input   type= "button "   value= "验证 "   onclick= "isNum() ">
</td> </tr>
</table>
</body>
</html>
我写了一个Demo，很原始，呵呵
<html>
<script   language= "javascript ">
function   isNum()
{
var   boolean   =false;
var   number   =   '0123456789 ';
var   str   =   document.getElementById( 'isNum ').value;
for(var   i=0;i <str.length;i++)
{
var   cur   =   str.charAt(i);
if(number.indexOf(cur)   ==   -1)
{
bo   =   false;
}else
{
bo   =   true;
}
}
if(bo)
{
alert( '合法字符 ');
}else
{
alert( '非法字符 ');
}
}
</script>
<body>
<table>
<tr> <td>
<input   type= "type "   name= "isNum ">
<input   type= "button "   value= "验证 "   onclick= "isNum() ">
</td> </tr>
</table>
</body>
</html>
isNaN(num) 返回是false 不是true