用isNaN(表达式)来判断!var s="hell0";
var j=parseInt(s);
if(isNaN(j)){
alert("This is not a number");
}
else{
alert("This is a number");
}
var j=parseInt(s);
if(isNaN(j)){
alert("This is not a number");
}
else{
alert("This is a number");
}
if(isNaN(j)){
alert("This is not a number");
}
else{
alert("This is a number");
if( (j>=10)&&(j<=20) )
alert("ok!")
else
alert("error!");
}
非负:<input onblur="checkDecimalInput(this)"><br>
[-1,1]:<input onblur="checkDecimalInput(this,-1.000001,1.0000001)"><br>
(-1,1):<input onblur="checkDecimalInput(this,-1,1)"><br><script language=javascript>function checkDecimalInput(obj,min,max) //作用是将输入变成Number(10,6)格式,默认范围是非负。
{
obj.value=obj.value.replace(/ /g,""); //去空格
if (obj.value=="") return false;
if (obj.value.substr(0,1)==".") obj.value="0"+obj.value;
if (obj.value.substr(0,2)=="-.") obj.value=obj.value.replace("-.","-0.");
var r, re;
var s = obj.value ;
var theMin=-0.0000001;
var theMax=10000000000;
if (min!=null) theMin=min;
if (max!=null) theMax=max;
if (s.length==0) return false;
re = /-{0,1}\d{1,10}\.{0,1}\d{0,6}/i;
r = s.match(re); //取数
if (r==null)
{
obj.value="";
alert("!!!!请注意:\n您刚才输入的数值不正确,我们已进行了清除。");
obj.focus();
return false;
}
if ((r>=theMax)||(r<=theMin))
{
obj.value="";
alert("!!!!请注意:\n您刚才输入的数值超出允许范围,我们已进行了清除。");
obj.focus();
return false;
}
if ( r!=s)
{
obj.value=r;
alert("!!!!请注意:\n您刚才输入的数值不正确,我们已进行了修改。");
obj.select();
obj.focus();
return false;
}
obj.value=r;
}
</script>