StringBuilder.js

出自ProgWiki

目錄 1 用途 2 原始出處 3 改良版 4 使用範例

用途

• 仿 .Net FrameWork 的StringBuilder

原始出處

• JavaScript StringBuilder

改良版

// 原始出處
//	StringBuilder:	http://www.codeproject.com/jscript/stringbuilder.asp
//	sprintf:	http://jan.moesen.nu/code/javascript/sprintf-and-printf-in-javascript/
// 改良版
//			http://www.player.idv.tw/prog/index.php?title=JavaScript:StringBuilder
 
function StringBuilder(value)
{
    this.strings = new Array("");
    this.append(value);
}
 
// Appends the given value to the end of this instance.
StringBuilder.prototype.append = function (value)
{
    if (value)
    {
        this.strings.push(value);
    }
    return this;
}
 
// Appends the given format value to the end of this instance.
StringBuilder.prototype.appendFormat = function ()
{
	var arguments = StringBuilder.prototype.appendFormat.arguments;
 
	if (arguments.length > 0)
	{
		var value = arguments[0];
		for (var i = 1; i < arguments.length; ++i) 
		{
			value = value.replace("{"+(i-1)+"}", arguments[i]);
		}
		this.strings.push(value);
    }
    return this;
}
 
 
// Clears the string buffer
StringBuilder.prototype.clear = function ()
{
    this.strings.length = 1;
}
 
// Converts this instance to a String.
StringBuilder.prototype.toString = function ()
{
    return this.strings.join("");
}
 
//appendPrintf
StringBuilder.prototype.appendPrintf  = function ()
{
	var arguments = StringBuilder.prototype.appendPrintf.arguments;
	if (!arguments || arguments.length < 1 || !RegExp)
	{
		Error('Error at StringBuilder.prototype.appendPrintf');
		return this;
	}
 
	var str = arguments[0];
	var formats = {
		'%': function(val) {return '%';},
		'b': function(val) {return  parseInt(val, 10).toString(2);},
		'c': function(val) {return  String.fromCharCode(parseInt(val, 10));},
		'd': function(val) {return  parseInt(val, 10) ? parseInt(val, 10) : 0;},
		'u': function(val) {return  Math.abs(val);},
		'f': function(val, p) {return  (p > -1) ? Math.round(parseFloat(val) * Math.pow(10, p)) / Math.pow(10, p): parseFloat(val);},
		'o': function(val) {return  parseInt(val, 10).toString(8);},
		's': function(val) {return  val;},
		'x': function(val) {return  ('' + parseInt(val, 10).toString(16)).toLowerCase();},
		'X': function(val) {return  ('' + parseInt(val, 10).toString(16)).toUpperCase();}
	};
 
	var re = /([^%]*)%('.|0|\x20)?(-)?(\d+)?(\.\d+)?(%|b|c|d|u|f|o|s|x|X)(.*)/;
	var a = [], numSubstitutions = 0;
 
	while (a = re.exec(str))
	{
		var leftpart = a[1], pPad = a[2], pJustify = a[3], pMinLength = a[4];
		var pPrecision = a[5], pType = a[6], rightPart = a[7];
 
		numSubstitutions++;
		if (numSubstitutions >= arguments.length)
		{
			Error('Error! Not enough function arguments (' + (arguments.length - 1) + ', excluding the string)\nfor the number of substitution parameters in string (' + numSubstitutions + ' so far).');
			return this;			
		}
		var param = arguments[numSubstitutions];
		var subst = param;
		var formatsFunc = formats[pType];
 
		if (formatsFunc != null)
		{
			if (pType == 'f')		
			{
				var precision = (pPrecision && pType == 'f') ? parseInt(pPrecision.substring(1)) : -1;
				subst = formatsFunc(param, precision);		
			} else {
				subst = formatsFunc(param);		
			}
		}
		if (leftpart)
		{
			this.strings.push(leftpart);
		}
		if (subst)
		{
			this.strings.push(subst);
		}
		str = rightPart;
	}
	if (str)
	{
		this.strings.push(str);
	}
	return this;
}

使用範例

// create a StringBuilder
var sb = new StringBuilder();
 
// append some text
sb.append("Lorem ipsum dolor sit amet, consectetuer adipiscing elit, ");
// 串接2個 append
sb.append("sed diem nonummy nibh euismod tincidunt ut lacreet dolore ").append("magna aliguam erat volutpat.");
 
// get the full string value
var s = sb.toString();