输入数字
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
手机号码:<input type="text" id="txt" maxlength="11" onkeypress="ttt(this,event)">
<script>
function ttt(obj,ev){
if(ev.keyCode<48||ev.keyCode>57){
ev.preventDefault();
}
}
</script>
</body>
</html>
