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sprintf的JavaScript实现

 2010-09-14 13:20:29 来源:WEB开发网   
核心提示:比较完整的模拟sprintf函数功能,可用的格式化通配符:%% - 返回百分号本身%b - 二进制数字%c - ASCII对应的字符%d - 整数%f - 浮点数%o - 八进制数字%s - 字符串%x - 16进制数字 (小写字母形式)%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 (

比较完整的模拟sprintf函数功能。可用的格式化通配符:

%% - 返回百分号本身

%b - 二进制数字

%c - ASCII对应的字符

%d - 整数

%f - 浮点数

%o - 八进制数字

%s - 字符串

%x - 16进制数字 (小写字母形式)

%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):

+   (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)

-   (变量左对齐)

0   (使用0作为右对齐的填充字符)

[0-9] (设置变量的最小宽度)

.[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(/(%([%]|(-)?(+| )?(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;
   }
  }
 }
}

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