ascaii和string互转

function StringBuffer(){
	this.arr=[];
}
StringBuffer.prototype.append=function(str){
	this.arr.push(str);
	return this;
};
StringBuffer.prototype.toString=function(str){
	return this.arr.join('');
};
//字符转ascaii
function string2ascaii(str){
	var sb=new StringBuffer();
	for(var i=0;i<str.length;i++){
		var ch=str.charAt(i);
		if(/[\x00-\xff]/i.test(ch)){
			sb.append("\\").append(parseInt(ch.charCodeAt(0)).toString(8));
		}else{
			sb.append("\\u").append(parseInt(ch.charCodeAt(0)).toString(16));
		}
		
	}
	return sb.toString();
}
//ascaii 转字符
function ascaii2string(str){
	if(str==null){
		return str;
	}
	str=str.replace(/\\([1-7][0-7]?[0-7]?)/ig,function($0,$1){
		return String.fromCharCode(parseInt($1,8));
	}).replace(/\\u([1-9a-f][0-9a-f][0-9a-f][0-9a-f]?)/ig,function($0,$1){
		return String.fromCharCode(parseInt($1,16));
	});
	return str;
}