Im trying to get this remote binary file to read the bytes, which (of course) are supossed to come in the range 0..255. Since the response is given as a string, I need to use charCodeAt to get the numeric values for every character. I have come across the problem that charCodeAt returns the value in UTF8 (if im not mistaken), so for example the ASCII value 139 gets converted to 8249. This messes up my whole application cause I need to get those value as they are sent from the server.
The immediate solution is to create a big switch that, for every given UTF8 code will return the corresponding ASCII. But i was wondering if there is a more elegant and simpler solution. Thanks in advance.
The following code has been extracted from an answer to this StackOverflow question and should help you work around your issue.
function stringToBytesFaster ( str ) {
var ch, st, re = [], j=0;
for (var i = 0; i < str.length; i++ ) {
ch = str.charCodeAt(i);
if(ch < 127)
{
re[j++] = ch & 0xFF;
}
else
{
st = []; // clear stack
do {
st.push( ch & 0xFF ); // push byte to stack
ch = ch >> 8; // shift value down by 1 byte
}
while ( ch );
// add stack contents to result
// done because chars have "wrong" endianness
st = st.reverse();
for(var k=0;k<st.length; ++k)
re[j++] = st[k];
}
}
// return an array of bytes
return re;
}
var str = "\x8b\x00\x01\x41A\u1242B\u4123C";
alert(stringToBytesFaster(str)); // 139,0,1,65,65,18,66,66,65,35,67
I would recommend encoding the binary data is some character-encoding independent format like base64
Related
Introduction
I'm currently working on John Conway's Game of Life in js. I have the game working (view here) and i'm working on extra functionalities such as sharing your "grid / game" to your friends. To do this i'm extracting the value's of the grid (if the cell is alive or dead) into a long string of 0's and 1's.
This long string can be seen as binary code and im trying to "compress" it into a hexadecimal string by chopping the binary up into substrings with a lenght of 8 and then determining its hexadecimal value. decompressing works the other way around. Deviding the hex string into bits of two and determining its binary value.
parseInt('00011110', 2).toString(16); // returns '1e'
parseInt('1e', 16).toString(2); // returns '11110'
// Technically both representations still have the same decimal value
As shown above js will cut off the leading 0s since they're 'not needed'.
I've fixed this problem by looking if the lenght of the binary string returned by the function is 8, ifnot it adds enough 0s in front untill its length is exactly 8.
It could be that this function is not working correctly but i'm not sure.
It seems to work with small binary values.
please note you can only put in strings with a length devidable by 8
The problem
Longer binary strings don't seem to work (shown below) and this is probably not caused by overflow (that would probably result in a long row of 0s at the end).
EDIT:
var a = "1000011101110101100011000000001011111100111011010011110000000100101000000111111010111111110101100001100101110001100110110101000111110001001010110111001010100011010010111001110010111001101100000100001001101000001010101110001001001110101001110001001111010110011000010100001111000111000011000101010110010011101100000100011101101110110000100101000110011101101011011111010111001001000101000001001111010010010010100000110101101101110101110101010101111101100110101110100100110000010000000110000100000001110001011001011011000101111110101000100011010100011001000101111001000010001011001011100100110001101100001111110110000000111010100101110110101110110111001100000001001100111110000111001010111110110100010111001011101110011011100100111010001100010111100111011010111110111101010000111101010100011000000111000010101011101101011110010011001110000111100000111011111011000000100000010100001111110101001110001100011001"
a.length
904
var c = compress(a)
c
"87758c2fced3c4a07ebfd619719b51f12b72a34b9cb9b042682ae24ea713d66143c7c5593b0476ec2519dadf5c91413d24ad6dd7557d9ae93040611c596c5fa88d4645e422cb931b0fd80ea5daedcc04cf872bed172ee6e4e8c5e76bef5f546070abb5e4ce1eefb25fd4e319"
var d = decompress(c)
d
"100001110111010110001100001011111100111011010011110001001010000001111110101111111101011000011001011100011001101101010001111100010010101101110010101000110100101110011100101110011011000001000010011010000010101011100010010011101010011100010011110101100110000101000011110001111100010101011001001110110000010001110110111011000010010100011001110110101101111101011100100100010100000100111101001001001010110101101101110101110101010101111101100110101110100100110000010000000110000100011100010110010110110001011111101010001000110101000110010001011110010000100010110010111001001100011011000011111101100000001110101001011101101011101101110011000000010011001111100001110010101111101101000101110010111011100110111001001110100011000101111001110110101111101111010111110101010001100000011100001010101110110101111001001100111000011110111011111011001001011111110101001110001100011001"
d == a
false
end of edit
My code
The function I use to compress:
function compress(bin) {
bin = bin.toString(); // To make sure the binary is a string;
var returnValue = ''; // Empty string to add our data to later on.
for (var i = 0; i < parseInt(bin.length / 8); i++) {
// Determining the substring.
var substring = bin.substr(i*8, 8)
// Determining the hexValue of this binary substring.
var hexValue = parseInt(substring, 2).toString(16);
// Adding this hexValue to the end string which we will return.
returnValue += hexValue;
}
// Returning the to hex compressed string.
return returnValue;
}
The function I use to decompress:
function decompress(compressed) {
var returnValue = ''; // Empty string to add our data to later on.
for (var i = 0; i < parseInt(compressed.length / 2); i++) {
// Determining the substring.
var substring = compressed.substr(i*2, 2);
// Determining the binValue of this hex substring.
var binValue = parseInt(substring, 16).toString(2);
// If the length of the binary value is not equal to 8 we add leading 0s (js deletes the leading 0s)
// For instance the binary number 00011110 is equal to the hex number 1e,
// but simply running the code above will return 11110. So we have to add the leading 0s back.
if (binValue.length != 8) {
// Determining how many 0s to add:
var diffrence = 8 - binValue.length;
// Adding the 0s:
for (var j = 0; j < diffrence; j++) {
binValue = '0'+binValue;
}
}
// Adding the binValue to the end string which we will return.
returnValue += binValue
}
// Returning the decompressed string.
return returnValue;
}
Does anyone know what's going wrong? Or how to do this properly?
Problem is you are expecting your compress function to always add pairs of 2 hexa letters, but that is not always the case. For example '00000011' gives just a '3', but you actually want '03'. So you need to cover those cases in your compress function:
var hexValue = parseInt(substring, 2).toString(16);
if(hexValue.length == 1) hexValue = '0'+hexValue
I'm trying to generate the public key from the following x and y of object Q in the browser. The problem is in order to use this public key for verifying a JWT I have to get the hexadecimal format of the key. I'm using keypair from the src="bitcoinjs.min.js" which does not allow me to retrieve the hexadecimal form of public key.
Is there any library or function to convert it into hexadecimal form?
// Taking reference from http://procbits.com/2013/08/27/generating-a-bitcoin-address-with-javascript
var pubX = hdnode.keyPair.Q.x.toByteArrayUnsigned();
var pubY = hdnode.keyPair.Q.y.toByteArrayUnsigned();
var publicKeyBytes = pubX.concat(pubY);
publicKeyBytes.unshift(0x04);
meanwhile I tried
<script src="http://peterolson.github.com/BigInteger.js/BigInteger.min.js"></script>
var publicKeyInt = BigInt.fromByteArrayUnsigned(publicKeyBytes);
but it's not working
Thanks in Advance
Ok so I'm going to expand on my comment
Assume: key is an array or an iterable of bytes
function getHexArray(key) {
function num2hex(num) {
return num > 9 ? num + 55 : num + 48;
}
var hex_key = [];
var lower, upper;
for (var i = 0; i < key.length; i++) {
lower = key[i] & 0x0f;
upper = key[i] >> 4;
return String.fromCharCode(num2hex(upper)) +
String.fromCharCode(num2hex(lower));
}
return hex_key;
}
Note that if you want a long string of hex, you probably want to reverse the order of lower and upper (this is for writing as an array of hex bytes)
This function allows you to put in an array of bytes and will output an array of 2-char strings representing the hex value of the bytes.
WORKING:
below is the piece of working code which is taking a byte array and gives out a hexadecimal string.
function toHexString(bytes) {
return bytes.map(function(byte) {
return (byte & 0xFF).toString(16)
}).join('')
}
Thanks #derekdreery for your help :)
Say I have an element like this...
<math xmlns="http://www.w3.org/1998/Math/MathML">
<mo class="symbol">α</mo>
</math>
Is there a way to get the unicode/hex value of alpha α, α, using JavaScript/jQuery? Something like...
$('.symbol').text().unicode(); // I know unicode() doesn't exist
$('.symbol').text().hex(); // I know hex() doesn't exist
I need α instead of α and it seems like anytime I insert α into the DOM and try to retrieve it right away, it gets rendered and I can't get α back; I just get α.
Using mostly plain JavaScript, you should be able to do:
function entityForSymbolInContainer(selector) {
var code = $(selector).text().charCodeAt(0);
var codeHex = code.toString(16).toUpperCase();
while (codeHex.length < 4) {
codeHex = "0" + codeHex;
}
return "&#x" + codeHex + ";";
}
Here's an example: http://jsfiddle.net/btWur/
charCodeAt will get you the decimal value of the string:
"α".charCodeAt(0); //returns 945
0x03b1 === 945; //returns true
toString will then get the hex string
(945).toString(16); // returns "3b1"
(Confirmed to work in IE9 and Chrome)
If you would try to convert Unicode character out of BMP (basic multilingual plane) in ways above - you are up for a nasty surprise. Characters out of BMP are encoded as multiple UTF16 values for example:
"🔒".length = 2 (one part for shackle one part for lock base :) )
so "🔒".charCodeAt(0) will give you 55357 which is only 'half' of number while "🔒".charCodeAt(1) will give you 56594 which is the other half.
To get char codes for those values you might wanna use use following string extension function
String.prototype.charCodeUTF32 = function(){
return ((((this.charCodeAt(0)-0xD800)*0x400) + (this.charCodeAt(1)-0xDC00) + 0x10000));
};
you can also use it like this
"&#x"+("🔒".charCodeUTF32()).toString(16)+";"
to get html hex codes.
Hope this saves you some time.
for example in case you need to convert this hex code to unicode
e68891e4bda0e4bb96
pick two character time by time ,
if the dec ascii code is over 127 , add a % before
return url decode string
function hex2a(hex) {
var str = '';
for (var i = 0; i < hex.length; i += 2){
var dec = parseInt(hex.substr(i, 2), 16);
character = String.fromCharCode(dec);
if (dec > 127)
character = "%"+hex.substr(i,2);
str += character;
}
return decodeURI(str);
}
I want to convert numbers into alpha characters using JavaScript. For example, 01=n, 02=i 03=n, 04=a, etc.
When someone enters the numbers:01020304 in the form he will get the response: nina. Whatever the user enters gets replaced with the equivalent characters including spaces.
Update
Thank you all for quick response. I have found this code in one site. It converts alpha characters into numbers, but code for converting numbers into alpha characters isn't working. Here is the code for converting alpha characters into numbers:
var i,j;
var getc;
var len;
var num, alpha;
num=new Array("01","02","03","04","05","06","07","08","09","10","11","12","13","14","15","16","17",
"18","19","20","21","22","23","24","25","26","00","##","$$");
alpha=new Array("a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","
v","w","x","y","z"," ",".",",");
function encode() {
len=document.f1.ta1.value.length;
document.f1.ta2.value="";
for(i=0;i<len;i++) {
getc=document.f1.ta1.value.charAt(i);
getc=getc.toLowerCase();
for(j=0;j<alpha.length;j++) {
if(alpha[j]==getc) {
document.f1.ta2.value+=num[j];
}
}
}
}
Can anyone show me how to convert this to do the opposite character conversion?
I agree with Skrilldrick, you should learn how to do this yourself, but I couldn't help myself: http://jsfiddle.net/dQkxw/
HTML
<html>
<body>
<input type="text" id="code">
<button onclick="decode($('#code').val())">
Decode
</button>
</body>
</html>
JavaScript
window.decode = function(numbers) {
if (numbers.length % 2 != 0)
{
alert("invalid code!");
return;
}
var result = "";
for (var i = 0; i < numbers.length; i+=2) {
var number = Number(numbers.substring(i, i+2));
if (number < 1 || number > 26)
{
alert("invalid number: "+number);
return;
}
result += String.fromCharCode(96+number);
}
alert(result);
}
A good way to do this easily, and so it is a scalable solution would be to have a multi dimensional array that maps each char to it's corresponding char. You can have multiple dimensions for each conversion and pick between them.
var myCharArray=new Array(4)
for (i=0; i < 4; i++)
myCharArray[i]=new Array(2)
myCharArray[0][0]="a"
myCharArray[0][1]="1"
myCharArray[1][0]="b"
myCharArray[1][1]="2"
myCharArray[2][0]="c"
myCharArray[2][1]="3"
myCharArray[3][0]="d"
myCharArray[3][1]="4"
Then, upon conversion, loop every single character in your string to be encoded, and search for it in the array. If it is found, switch it with the encoded value. This should be reasonably easy to do.
The method you described seems to be a simple derivative off a Caesar cipher. Also remember because the script is client side, it will be incredible easy to decode, so make sure it's not for anything important!
I am attempting to help my teacher convert a Greek textbook into an online application. Part of this includes taking a Shapefile ( draws polygons on maps, along with descriptions of the polygons. ) and mapping everything on this map. I cannot directly access the part of the shapefile file that has the data I need to convert due to it being in hexadecimal.
Anyways, here is the code that I am printing to my console.
console.log((arr[1][i]['PERIOD']);
"arr" is the data array that contains all of the properties that I want to convert from Greek into UTF-8. I am only printing "PERIOD", rather than the 12 other propierties that are associated with the array.
When I run my page, the console returns several variations of text(as there exist several periods.) Here is an example of the text it returns.
ÎÏÏαÏκή, ÎλαÏική, ÎλληνιÏÏική
ΡÏμαÏκή
ÎθÏμανική
Î¥ÏÏεÏοβÏζανÏινή
Believe it or not, but this is not Greek text. So I snooped around and found this function to convert to utf-8:
function encode_utf8( s ){
return unescape(encodeURI( s ));
}
When I add this function to my console.log, this is what I get:
áÃÂüñÃÂúî
ÃÂøÃÂüñýùúî
ÃÂ¥ÃÂÃÂõÃÂÿòÃÂöñýÃÂùýî
ÃÂøÃÂüñýùúî
I am not 100% positive but I think that the text I am trying to convert is currently in ISO-8859-7.
Any help with this would be amazing.
Thank you.
You quite easily can build a map of the bytes of one char set to another (although it can get tedious)
Assuming ISO 8859-7 which is only 256 bytes long so not too difficult,
function genCharMap() { // ISO 8859-7 to Unicode
var map = [], i, j, str;
map.length = 256;
map[0] = 0; // fill in 0
str = '\u2018\u2019\u00a3\u20ac\u20af\u00a6\u00a7\u00a8\u00a9\u037a\u00ab\u00ac\u00ad\u00ae\u2015\u00b0\u00b1\u00b2\u00b3\u0384\u0385\u0386\u00b7\u0388\u0389\u038a\u00bb\u038c\u00bd\u038e';
for (i = 0; i < str.length; ++i) // fill in 0xA1 to 0xBE
map[0xA1 + i] = str.charCodeAt(i);
for (i = 0; i < 256; ++i) // fill in blanks
if (i in map) j = map[i] - i;
else map[i] = j + i;
return map;
}
Now you can apply this transformation to your bytes
var byteArr = [0xC1, 0xE2, 0xE3, 0xE4], // Αβγδ
str_out = '',
i,
map = genCharMap();
for (i = 0; i < byteArr.length; ++i) {
str_out += String.fromCharCode(
map[byteArr[i]]
);
}
str_out; // "Αβγδ"
If you're re-writing this code for a charset with "combining chars" it may be safer to swap the str I used in genCharMap for an Array of numbers instead.