arr2hexString.js

/**** save an array of integer to an hexa string and back ***///

	function num2b(num, len){
		var arr = [],
			top = 32-len,
			mask=(2<<(len-1))-1,//len:1 is binary
			v = num>>>top,
			lead=false;
		
		if(v!==0){
			arr.push(v.toString(16));
			lead=true;
		}
		
		while(top){
			top-=len;
			v=num>>top&mask;
			
			if(lead||v!==0){
				arr.push(v.toString(16));
				lead=true;
			}
		}
		
		return arr;
	}
	
	function arr2str(arr){
		var arr_str = "", 
			num_str, 
			num_arr, 
			num,
			num_len,
			j;
			
		for(var i=0, l=arr.length; i<l; i++){
			num_l = arr[i];
			num_str = "";
			num_arr = num2b(num_l, 4);
			num_len=num_arr.length;
			arr_str+=num_len.toString(16)+num_arr.join("");
		}
		
		return arr_str;
	}
	
	function str2arr(str){
		var arr = [],
			n_l, n;
		
		for(var i=0, l=str.length; i<l; i++){
			n_l = parseInt(str.substr(i, 1), 16);
			n=parseInt(str.substr(i+1, n_l), 16);
			arr.push(n);
			i+=n_l;
		}
		return arr;
	}
	
	var arr_to_save = [ 4, 8, 15, 16, 23, 42, 4294967295],
		saved_str = arr2str(arr_to_save);
	
	console.log(saved_str);
	
	var arr_restored = str2arr(saved_str);
	console.log(arr_restored);