JavaScript中实现sprintf、printf函数

在 JavaScript 下实现大多数语言中都有的 sprintf / printf 函数功能。

http://www.webtoolkit.info/javascript-sprintf.html : 比较完整的模拟sprintf函数功能。可用的格式化通配符：
1.%% - 返回百分号本身
2.%b - 二进制数字
3.%c - ASCII对应的字符
4.%d - 整数
5.%f - 浮点数
6.%o - 八进制数字
7.%s - 字符串
8.%x - 16进制数字 (小写字母形式)
9.%X - 16进制数字 (大写字母形式)

在 % 号和通配字符之间可用的选项包括 (比如 %.2f)：

1.+      (强制在数字前面显示 + 和 - 符号作为正负数标记。缺省情况下只有负数才显示 - 符号)
2.-      (变量左对齐)
3.0      (使用0作为右对齐的填充字符)
4.[0-9]  (设置变量的最小宽度)
5..[0-9] (设置浮点数精度或字符串的长度)

代码如下:

/**
*
*  Javascript sprintf
*  http://www.webtoolkit.info/
*
*
**/

sprintfWrapper = {

init : function () {

if (typeof arguments == "undefined") { return null; }
    if (arguments.length < 1) { return null; }
    if (typeof arguments[0] != "string") { return null; }
    if (typeof RegExp == "undefined") { return null; }

var string = arguments[0];
    var exp = new RegExp(/(%([%]|(\-)?(\+|\x20)?(0)?(\d+)?(\.(\d)?)?([bcdfosxX])))/g);
    var matches = new Array();
    var strings = new Array();
    var convCount = 0;
    var stringPosStart = 0;
    var stringPosEnd = 0;
    var matchPosEnd = 0;
    var newString = '';
    var match = null;

while (match = exp.exec(string)) {
      if (match[9]) { convCount += 1; }

stringPosStart = matchPosEnd;
      stringPosEnd = exp.lastIndex - match[0].length;
      strings[strings.length] = string.substring(stringPosStart, stringPosEnd);

matchPosEnd = exp.lastIndex;
      matches[matches.length] = {
        match: match[0],
        left: match[3] ? true : false,
        sign: match[4] || '',
        pad: match[5] || ' ',
        min: match[6] || 0,
        precision: match[8],
        code: match[9] || '%',
        negative: parseInt(arguments[convCount]) < 0 ? true : false,
        argument: String(arguments[convCount])
      };
    }
    strings[strings.length] = string.substring(matchPosEnd);

if (matches.length == 0) { return string; }
    if ((arguments.length - 1) < convCount) { return null; }

var code = null;
    var match = null;
    var i = null;

for (i=0; i<matches.length; i++) {

if (matches[i].code == '%') { substitution = '%' }
      else if (matches[i].code == 'b') {
        matches[i].argument = String(Math.abs(parseInt(matches[i].argument)).toString(2));
        substitution = sprintfWrapper.convert(matches[i], true);
      }
      else if (matches[i].code == 'c') {
        matches[i].argument = String(String.fromCharCode(parseInt(Math.abs(parseInt(matches[i].argument)))));
        substitution = sprintfWrapper.convert(matches[i], true);
      }
      else if (matches[i].code == 'd') {
        matches[i].argument = String(Math.abs(parseInt(matches[i].argument)));
        substitution = sprintfWrapper.convert(matches[i]);
      }
      else if (matches[i].code == 'f') {
        matches[i].argument = String(Math.abs(parseFloat(matches[i].argument)).toFixed(matches[i].precision ? matches[i].precision : 6));
        substitution = sprintfWrapper.convert(matches[i]);
      }
      else if (matches[i].code == 'o') {
        matches[i].argument = String(Math.abs(parseInt(matches[i].argument)).toString(8));
        substitution = sprintfWrapper.convert(matches[i]);
      }
      else if (matches[i].code == 's') {
        matches[i].argument = matches[i].argument.substring(0, matches[i].precision ? matches[i].precision : matches[i].argument.length)
        substitution = sprintfWrapper.convert(matches[i], true);
      }
      else if (matches[i].code == 'x') {
        matches[i].argument = String(Math.abs(parseInt(matches[i].argument)).toString(16));
        substitution = sprintfWrapper.convert(matches[i]);
      }
      else if (matches[i].code == 'X') {
        matches[i].argument = String(Math.abs(parseInt(matches[i].argument)).toString(16));
        substitution = sprintfWrapper.convert(matches[i]).toUpperCase();
      }
      else {
        substitution = matches[i].match;
      }

newString += strings[i];
      newString += substitution;

}
    newString += strings[i];

return newString;

},

convert : function(match, nosign){
    if (nosign) {
      match.sign = '';
    } else {
      match.sign = match.negative ? '-' : match.sign;
    }
    var l = match.min - match.argument.length + 1 - match.sign.length;
    var pad = new Array(l < 0 ? 0 : l).join(match.pad);
    if (!match.left) {
      if (match.pad == "0" || nosign) {
        return match.sign + pad + match.argument;
      } else {
        return pad + match.sign + match.argument;
      }
    } else {
      if (match.pad == "0" || nosign) {
        return match.sign + match.argument + pad.replace(/0/g, ' ');
      } else {
        return match.sign + match.argument + pad;
      }
    }
  }
}

sprintf = sprintfWrapper.init;

如果只是想进行简单的位置变量内容替换而不需要额外的格式化处理的话，可以用比较简单的 YUI tools 中所提供的printf：

代码如下:

YAHOO.Tools.printf = function() {
  var num = arguments.length;
  var oStr = arguments[0];
  for (var i = 1; i < num; i++) {
    var pattern = "\\{" + (i-1) + "\\}";
    var re = new RegExp(pattern, "g");
    oStr = oStr.replace(re, arguments[i]);
  }
  return oStr;
}

使用的时候像 YAHOO.Tools.printf("显示字符串 {0} ， {1}。", "1", "2"); 这样用{?}来做匹配。