Это, наверное, плохая идея ...
<!doctype html>
<html lang="en">
<head>
<meta charset= "utf-8">
<title>Comma Thousands Input</title>
<style>
label, input, button{font-size:1.25em}
</style>
<script>
// insert commas as thousands separators
function addCommas(n){
var rx= /(\d+)(\d{3})/;
return String(n).replace(/^\d+/, function(w){
while(rx.test(w)){
w= w.replace(rx, '$1,$2');
}
return w;
});
}
// return integers and decimal numbers from input
// optionally truncates decimals- does not 'round' input
function validDigits(n, dec){
n= n.replace(/[^\d\.]+/g, '');
var ax1= n.indexOf('.'), ax2= -1;
if(ax1!= -1){
++ax1;
ax2= n.indexOf('.', ax1);
if(ax2> ax1) n= n.substring(0, ax2);
if(typeof dec=== 'number') n= n.substring(0, ax1+dec);
}
return n;
}
window.onload= function(){
var n1= document.getElementById('number1'),
n2= document.getElementById('number2');
n1.value=n2.value='';
n1.onkeyup= n1.onchange=n2.onkeyup=n2.onchange= function(e){
e=e|| window.event;
var who=e.target || e.srcElement,temp;
if(who.id==='number2') temp= validDigits(who.value,2);
else temp= validDigits(who.value);
who.value= addCommas(temp);
}
n1.onblur= n2.onblur= function(){
var temp=parseFloat(validDigits(n1.value)),
temp2=parseFloat(validDigits(n2.value));
if(temp)n1.value=addCommas(temp);
if(temp2)n2.value=addCommas(temp2.toFixed(2));
}
}
</script>
</head>
<body>
<h1>Input Thousands Commas</h1>
<div>
<p>
<label> Any number <input id="number1" value=""></label>
<label>2 decimal places <input id="number2" value=""></label>
</p></div>
</body>
</html>