how to make input html only number type in javascript code example

Example 1: type numeric value only in textbox javascript

function isNumber(evt) {
    evt = (evt) ? evt : window.event;
    var charCode = (evt.which) ? evt.which : evt.keyCode;
    if (charCode > 31 && (charCode < 48 || charCode > 57)) {
        return false;
    }
    return true;
}

Example 2: input text tag only input integer number

<input type="text" class="number" />

<script>
function degitOnly(e){
    var unicode = e.charCode ? e.charCode : e.keyCode;
      if (unicode!=8 && unicode!=9)
     {
     	 if (unicode<46||unicode>57||unicode==47)
     		 return false
    }
}

$(".number").inputFilter(function(value) {
    return /^-?\d*$/.test(value);
});
</script>