Question

I have some client-side validation against a text box, which only allows numbers up to two decimal places with no other input.

This script was a basis for entering numeric values only, however it needs to be adapted so it can take a decimal point followed by only up to two decimal places.

I’ve tried things such as /[^\d].\d{0,2}, but then the replacement call wouldn’t work, and I’ve got no idea how to do it.

Code

<script type='text/JavaScript'>   function valid(f) {     if (!/^\d*$/.test(f.value)) {       f.value = f.value.replace(/[^\d]/g,'');       alert('Invalid number');     }   } </script> 

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Note

I need to match an empty string. If an empty string is provided and the form is submitted, the value defaults back to zero.

Answer 1

The . character has special meaning in RegEx so needs escaping.

/^(?:\d*\.\d{1,2}|\d+)$/ 

This matches 123.45, 123.4, 123 and .2, .24 but not emtpy string, 123., 123.456