If you're doing this to several fields, or doing it quite often, then perhaps a plugin is the answer.
Here's the beginnings of a jQuery plugin that formats the value of a field to two decimal places.
It is triggered by the onchange event of the field. You may want something different.
<script type="text/javascript">
// mini jQuery plugin that formats to two decimal places
(function($) {
$.fn.currencyFormat = function() {
this.each( function( i ) {
$(this).change( function( e ){
if( isNaN( parseFloat( this.value ) ) ) return;
this.value = parseFloat(this.value).toFixed(2);
});
});
return this; //for chaining
}
})( jQuery );
// apply the currencyFormat behaviour to elements with 'currency' as their class
$( function() {
$('.currency').currencyFormat();
});
</script>
<input type="text" name="one" class="currency"><br>
<input type="text" name="two" class="currency">