javascript为数字添加逗号千分符详解编程语言

function CommaFormatted(amount) { 
    var delimiter = ","; // replace comma if desired 
    var a = amount.split('.',2) 
    var d = a[1]; 
    var i = parseInt(a[0]); 
    if(isNaN(i)) { return ''; } 
    var minus = ''; 
    if(i < 0) { minus = '-'; } 
    i = Math.abs(i); 
    var n = new String(i); 
    var a = []; 
    while(n.length > 3) { 
        var nn = n.substr(n.length-3); 
        a.unshift(nn); 
        n = n.substr(0,n.length-3); 
    } 
    if(n.length > 0) { a.unshift(n); } 
    n = a.join(delimiter); 
    if(d.length < 1) { amount = n; } 
    else { amount = n + '.' + d; } 
    amount = minus + amount; 
    return amount; 
}