JavaScript格式化数字显示格式_function formatnumber(num, pattern)-优快云博客

本文介绍了一个实用的JavaScript函数，用于按指定模式格式化数字。该函数支持千位分隔符和固定小数位数，适用于财务报表等场景。示例展示了不同格式模式的应用。

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/**
* 格式化数字显示方式
* 用法
* formatNumber(12345.999,'#,##0.00');
* formatNumber(12345.999,'#,##0.##');
* formatNumber(123,'000000');
* @param num
* @param pattern
*/
function formatNumber(num,pattern){
var strarr = num?num.toString().split('.'):['0'];
var fmtarr = pattern?pattern.split('.'):[''];
var retstr='';

// 整数部分
var str = strarr[0];
var fmt = fmtarr[0];
var i = str.length-1;
var comma = false;
for(var f=fmt.length-1;f>=0;f--){
    switch(fmt.substr(f,1)){
      case '#':
        if(i>=0 ) retstr = str.substr(i--,1) + retstr;
        break;
      case '0':
        if(i>=0) retstr = str.substr(i--,1) + retstr;
        else retstr = '0' + retstr;
        break;
      case ',':
        comma = true;
        retstr=','+retstr;
        break;
    }
}
if(i>=0){
    if(comma){
      var l = str.length;
      for(;i>=0;i--){
        retstr = str.substr(i,1) + retstr;
        if(i>0 && ((l-i)%3)==0) retstr = ',' + retstr;
      }
    }
    else retstr = str.substr(0,i+1) + retstr;
}

retstr = retstr+'.';
// 处理小数部分
str=strarr.length>1?strarr[1]:'';
fmt=fmtarr.length>1?fmtarr[1]:'';
i=0;
for(var f=0;f<fmt.length;f++){
 switch(fmt.substr(f,1)){
 case '#':
 if(i<str.length) retstr+=str.substr(i++,1);
 break;
 case '0':
 if(i<str.length) retstr+= str.substr(i++,1);
 else retstr+='0';
 break;
 }
}
return retstr.replace(/^,+/,'').replace(/\.$/,'');
}

document.write("formatNumber('','')=" + formatNumber('',''));
document.write(" ");
document.write("formatNumber(123456789012.129,null)=" + formatNumber(123456789012.129,null));
document.write(" ");
document.write("formatNumber(null,null)=" + formatNumber(null,null));
document.write(" ");
document.write("formatNumber(123456789012.129,'#,##0.00')=" + formatNumber(123456789012.129,'#,##0.00'));
document.write(" ");
document.write("formatNumber(123456789012.129,'#,##0.##')=" + formatNumber(123456789012.129,'#,##0.##'));
document.write(" ");
document.write("formatNumber(123456789012.129,'#0.00')=" + formatNumber(123456789012.129,'#,##0.00'));
document.write(" ");
document.write("formatNumber(123456789012.129,'#0.##')=" + formatNumber(123456789012.129,'#,##0.##'));
document.write(" ");
document.write("formatNumber(12.129,'0.00')=" + formatNumber(12.129,'0.00'));
document.write(" ");
document.write("formatNumber(12.129,'0.##')=" + formatNumber(12.129,'0.##'));
document.write(" ");
document.write("formatNumber(12,'00000')=" + formatNumber(12,'00000'));
document.write(" ");
document.write("formatNumber(12,'#.##')=" + formatNumber(12,'#.##'));
document.write(" ");
document.write("formatNumber(12,'#.00')=" + formatNumber(12,'#.00'));
document.write(" ");
document.write("formatNumber(0,'#.##')=" + formatNumber(0,'#.##'));
document.write(" ");