Block Alphabet in text field using JavaScript

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In this article, I will demonstrate how to allow user to input only numeric characters in a TextBox field by using Javascript. The program prevents user from copying and pasting invalid characters into the TextBox.


function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57) && charCode != 46)
return false;
return true;
}