JS实现php的printf方法

原文地址：http://www.jb51.net/article/60398.htm（我知道这不是原作者，请知道的转告我jackqqq123@sina.com）

简单版

/*

var hangstr="this is {0},{1}";
printf(hangstr,"me","guy");
//result :this is me,guy
*/
function printf() {
  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;
}

完整功能

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)

/*
*/
/**
*
*  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;