hexdump tool, like linux "xxd" command.

hexdump.js

/**
 * @fileOverview  Hexdump util
 * @author ra <ra@rockagen.com>
 * @version 0.0.1
 * @see {@link http://usejsdoc.org|jsdoc}
 * @example
 * var stuff="30313233343536";// "0123456"
 * var retval=hexdump.pretty(hexdump.decode(stuff));
 * console.log(retval);
 *
 * //output
 *
 *          +-------------------------------------------------+
 *          |  0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F |
 * +--------+-------------------------------------------------+----------------+
 * |00000000| 30 31 32 33 34 35 36                            |0123453         |
 * +--------+-------------------------------------------------+----------------+
 *
 * //enjoy :)
 * 
 */

/**
 *@namespace hexdump
 */

(function(exports){


	/**
	 * Hex array
	 * @const
	 */
	exports.HEXARRAY="0123456789ABCDEF".split("");
	/**
	 * Hex string decode to bytes
	 * @param {String} hex
	 * @return {Array} bytes
	 */
	exports.decode=function(hex){

		var bytes=[];

		for( var i=0;i<hex.length;i+=2 ){
			bytes.push(parseInt(hex.substr(i, 2), 16));
		}
		return bytes;
	}; 


	/**
	 * Get bytes
	 * @param {String} str
	 * @return {Array} bytes
	 */
	exports.bin=function(str){

		var bytes=[];
		for(var i=0;i<str.length;i++){
			bytes.push(str.charCodeAt(i));
		}
		return bytes; 

	};

	/**
	 * Compact hex dump
	 * @param {Array} bytes
	 * @return {String} hex
	 */
	exports.compact=function(bytes){

		if(bytes === undefined)
			return "[no data]";


		var length=bytes.length;
		var temp;
		var hex =new Array(length * 2);

		for(var i=0;i<length; ++i){
			//UnsignedByte
			temp=bytes[i] & 0xFF;
			hex[i*2] = exports.HEXARRAY[temp >>> 4];
			hex[i*2 +1] = exports.HEXARRAY[temp & 0xFF];
		}

		return hex.join('');

	};

	/**
	 * Pretty hex dump
	 * @param {Array} bytes
	 * @return {String} pretty dump
	 */
	exports.pretty=function(bytes){

		if(bytes === undefined)
			return "[no data]";

		var length=bytes.length;

		var row=Math.ceil(length / 16.0);

		var newline="\n";
		var dump=newline;
		dump+="         +-------------------------------------------------+";
		dump+=newline;
		dump+="         |  0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F |";
		dump+=newline;
		dump+="+--------+-------------------------------------------------+----------------+";


		var hex, value, temp;

		for(var i=0;i<row;i++){

			var ridx=i *16;

			hex=Array.apply(null,   new Array(49)).map(String.prototype.valueOf,  ' ');
			value=Array.apply(null,   new Array(16)).map(String.prototype.valueOf,  ' ');

			for(var j=0;j<16;j++){

				if (ridx + j >= length)
					break;

				temp = bytes[ridx + j];

				// UnsignedByte
				temp = temp & 0xFF;

				hex[j * 3 + 1] = exports.HEXARRAY[temp >>> 4];
				hex[j * 3 + 2] = exports.HEXARRAY[temp & 0x0F];

				if (temp <= 0x1f || temp >= 0x7f) {
					value[j] = '.';
				} else {
					value[j] =String.fromCharCode(temp);
				} 
			}
			var offset0=ridx.toString(16);

			dump+=newline;
			dump+="|";
			dump+=Array.apply(null,   new Array(8-offset0.length)).map(String.prototype.valueOf,  '0').join('');
			dump+=offset0; // hex offset
			dump+="|";
			dump+=hex.join(''); // hex 
			dump+="|";
			dump+=value.join('');  // value
			dump+="|";

		}


		dump+=newline;
		dump+="+--------+-------------------------------------------------+----------------+";
		dump+=newline;

		return dump;

	};

})(typeof exports === 'undefined'?this.hexdump={}:exports);