js digital format (format truncation or rounding format)

/ *** 
* digital format (suitable financial products after truncating the decimal places to show) 
* @param NUM 
* @param pattern (standard format: # ### or # ## or # ##, ### 00.00 ) 
* @param after round 1 = rounded format; cutoff = 0 format 
* @Returns {String} 
* / 
function formatNumber (NUM, pattern, round) { 
 IF (NUM &&! /^[\d\.]+$ . / G Test (NUM)) { 
 Console. log ( "The Number the format IS here Incorrect!"); 
 return ""; 
} 

 var formatLeft = ""; 
 var formatRight = ""; 
 var symbolFlag = pattern. lastIndexOf ( "." );
 if (symbolFlag == -1) {
 formatLeft = pattern;
 } else {
 formatLeft = pattern.substring(0, pattern.lastIndexOf("."));
 formatRight = pattern.substring(pattern.lastIndexOf(".") + 1, pattern.length);
 }
 //四舍五入
 if (round == 1) {
 num = new Number(num).toFixed(formatRight.length);
 }

 //格式化数字
 var numberLeft = "";
 var numberRight = "";
 var numSymbolFlag = num.lastIndexOf(".");
 if (numSymbolFlag == -1) {
 var numberLeft = num;
 } else {
 var numberLeft = num.substring(0, num.lastIndexOf("."));
 var numberRight = num.substring(num.lastIndexOf(".") + 1, num.length);
 }

 var numberBucket = new Array();
 var formatFlag = formatLeft.indexOf("#,###");//千位符标记
 var count = 1;
 var len = numberLeft.length;
 for (var i = len; i > 0; i--) {
 numberBucket.unshift(numberLeft.charAt(i - 1));
 if (formatFlag != -1) {
 if (count % 3 == 0 && count != len) {
 numberBucket.unshift(',');
 }
 }
 count++;
 }
 if (symbolFlag != -1) {
 numberBucket.push('.');
 }
 for (var i = 0; i < formatRight.length; i++) {
 if (formatRight.charAt(i) && numberRight.charAt(i)) {
 numberBucket.push(numberRight.charAt(i))
 } else {
 numberBucket.push("0");
 }
 }
 return numberBucket.join("");
}

//测试
document.writeln(formatNumber("123456789.123456", "#") + "<br/>");
document.writeln(formatNumber("123456789.123456", "#.#")+ "<br/>");
document.writeln(formatNumber("123456789.123456", "#,###") + "<br/>");
document.writeln(formatNumber("123456789.123456", "#,###.#")+ "<br/>");
document.writeln(formatNumber("123456789.123456", "#,###.#")+ "<br/>");document.writeln(formatNumber("123456789.123456", "#,###.####")+ "<br/>");document.writeln(formatNumber("1.50", "#.#", 1) + "<br/>");document.writeln(formatNumber("1.125456", "#.#", 1) + "<br/>");document.writeln(formatNumber("1.125456", "#.##", 1) + "<br/>");
document.writeln(formatNumber("1.125456", "#.###", 1) + "<br/>");
document.writeln(formatNumber("1.125456", "#.####", 1) + "<br/>");
document.writeln(formatNumber("1.125456", "#.#####", 1) + "<br/>");