javascript 小数位

<script>
var x;
//////////////////////////////////
document.write('<b>小数点左侧每三位数字之间不以逗号
分隔，小数点右侧取两位数</b><hr>');
function formatNum1(a){
   var aa=a.toString();
   var r;
   var i=aa.indexOf('.');
   if(i>-1){
       aa=aa=a+'00';
       r=aa.substring(0,i+3);
       }
       else{
       r=aa+".00";
       }
       return r;
//return Math.round(a*100)/100;
}
x=formatNum1(12002545454874.3295);
document.write(x+'<br>');
x=formatNum1(12002545454874.3);
document.write(x+'<br>');
x=formatNum1(12002545454874);
document.write(x+'<br>');

/////////////////////////////
document.write('<b>小数点左侧每三位数字之间以逗号分
隔，小数点右侧取两位数</b><hr>');
function formatNum2(a){
     var b = parseFloat(a);
     var tempConvert = b.toLocaleString();
     if (tempConvert.charAt(0) == "."){
          tempConvert = 0+tempConvert;
     }
     return tempConvert;
}
x=formatNum2(12002545454874.3295);
document.write(x+'<br>');
x=formatNum2(12002545454874.3);
document.write(x+'<br>');
x=formatNum2(12002545454874);
document.write(x+'<br>');
x=formatNum2(74);
document.write(x+'<br>');

/////////////////////////////////
document.write('<b>小数点左侧每三位数字之间不以逗号
分隔，小数点右侧取四位数</b><hr>');
function formatNum3(a){
   var aa=a.toString();
   var r;
   var i=aa.indexOf('.');
   if(i>-1){
       aa=aa+"0000";
       r=aa.substring(0,i+5);
       }
       else{
       r=aa+".0000";
       }
       return r;
}
x=formatNum3(122204.39552);
document.write(x+'<br>');
x=formatNum3(12002545454874.3);
document.write(x+'<br>');
x=formatNum3(12002545454874);
document.write(x+'<br>');

</script>
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