Hexdump in javascript

hexdump.js

// Modified version of https://gist.github.com/igorgatis/d294fe714a4f523ac3a3
        function hexdump(buffer, blockSize, maxLength) {
          if(typeof buffer === 'string'){
            console.log("buffer is string");
            //do nothing
          }else if(buffer instanceof ArrayBuffer && buffer.byteLength !== undefined){
            console.log("buffer is ArrayBuffer");
            var tlen = buffer.byteLength;
            if (tlen > 65000) tlen = 65000;
            buffer = String.fromCharCode.apply(String, [].slice.call(new Uint8Array(buffer, 0, tlen)));
          }else if(Array.isArray(buffer)){
            console.log("buffer is Array");
            buffer = String.fromCharCode.apply(String, buffer);
          }else if (buffer.constructor === Uint8Array) {
            console.log("buffer is Uint8Array");
            buffer = String.fromCharCode.apply(String, [].slice.call(buffer));
          }else{
            console.log("Error: buffer is unknown...");
            return false;
          }

          blockSize = blockSize || 16;
            var lines = [];
            var hex = "0123456789ABCDEF";

            // do not show more than maxLength bytes
            maxLength = maxLength || buffer.length;
            var length = buffer.length;
            var truncated = false;
            if (length > maxLength ) {
              length = maxLength;
              truncated = true;
            }

            for (var b = 0; b < length; b += blockSize) {
                var block = buffer.slice(b, Math.min(b + blockSize, length));
                var addr = ("0000" + b.toString(16)).slice(-4);
                var codes = block.split('').map(function (ch) {
                    var code = ch.charCodeAt(0);
                    return " " + hex[(0xF0 & code) >> 4] + hex[0x0F & code];
                }).join("");
                codes += "   ".repeat(blockSize - block.length);
                var chars = block.replace(/[\x00-\x1F\x20]/g, '.');
                chars +=  " ".repeat(blockSize - block.length);
                lines.push(addr + " " + codes + "  " + chars);
            }
            if (truncated) {
                lines.push("Truncated from " + buffer.length + " to " + maxLength);
            }
            return lines.join("\n");
        }

        //tests:
        var buffer = 'very very long string; very very long string; very very long string;';		//long string	- working
        console.log( hexdump( buffer , 16 ) ) ;
        var buffer = new Uint8Array([1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]).buffer;	//arrayBuffer	- working
        console.log( hexdump( buffer , 16 ) ) ;
        console.log( hexdump( buffer , 16 , 32 ) ) ; // only show 32 bytes at max
        var buffer = new Uint8Array([21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40]);	//Uint8Array	- working
        console.log( hexdump( buffer , 16 ) ) ;
        var buffer = [41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60];			//bytearray	- working
        console.log( hexdump( buffer , 16 ) ) ;