JS 格式化数字

<script>
/**
 * 格式化数字
 * @param number
 * @param pattern
 * @return
 */
function formatNumber(number,pattern){
    var str            = number.toString();
    var strInt;
    var strFloat;
    var formatInt;
    var formatFloat;
    if(/\./g.test(pattern)){
        formatInt        = pattern.split('.')[0];
        formatFloat        = pattern.split('.')[1];
    }else{
        formatInt        = pattern;
        formatFloat        = null;
    }

    if(/\./g.test(str)){
        if(formatFloat!=null){
            var tempFloat    = Math.round(parseFloat('0.'+str.split('.')[1])*Math.pow(10,formatFloat.length))/Math.pow(10,formatFloat.length);
            strInt        = (Math.floor(number)+Math.floor(tempFloat)).toString();                
            strFloat    = /\./g.test(tempFloat.toString())?tempFloat.toString().split('.')[1]:'0';            
        }else{
            strInt        = Math.round(number).toString();
            strFloat    = '0';
        }
    }else{
        strInt        = str;
        strFloat    = '0';
    }
    if(formatInt!=null){
        var outputInt    = '';
        var zero        = formatInt.match(/0*$/)[0].length;
        var comma        = null;
        if(/,/g.test(formatInt)){
            comma        = formatInt.match(/,[^,]*/)[0].length-1;
        }
        var newReg        = new RegExp('(\\d{'+comma+'})','g');

        if(strInt.length<zero){
            outputInt        = new Array(zero+1).join('0')+strInt;
            outputInt        = outputInt.substr(outputInt.length-zero,zero)
        }else{
            outputInt        = strInt;
        }

        var 
        outputInt            = outputInt.substr(0,outputInt.length%comma)+outputInt.substring(outputInt.length%comma).replace(newReg,(comma!=null?',':'')+'$1')
        outputInt            = outputInt.replace(/^,/,'');

        strInt    = outputInt;
    }

    if(formatFloat!=null){
        var outputFloat    = '';
        var zero        = formatFloat.match(/^0*/)[0].length;

        if(strFloat.length<zero){
            outputFloat        = strFloat+new Array(zero+1).join('0');
            //outputFloat        = outputFloat.substring(0,formatFloat.length);
            var outputFloat1    = outputFloat.substring(0,zero);
            var outputFloat2    = outputFloat.substring(zero,formatFloat.length);
            outputFloat        = outputFloat1+outputFloat2.replace(/0*$/,'');
        }else{
            outputFloat        = strFloat.substring(0,formatFloat.length);
        }

        strFloat    = outputFloat;
    }else{
        if(pattern!='' || (pattern=='' && strFloat=='0')){
            strFloat    = '';
        }
    }

    return strInt+(strFloat==''?'':'.'+strFloat);
}

 alert(formatNumber(2000,'######,###'));
</script>