Base 16 encoding of Uint8Array.buffer data - javascript

I am using javascript Uint8Array object.
I get a binary data out of it using '.buffer' property.
Due to some reasons I want to encode the binary data to base16 but I haven't got the clue yet.
Any help in the regard would be helpful.

Not sure if this is what you need
var b16 = "";
var u8 = [8,9,10,11]; // sample input
for(var x = 0; x < u8.length; x++) {
b16 += pad2(u8[x].toString(16));
}
function pad2(str) {
return (str.length < 2) ? "0"+str : str;
}
console.log(b16); // will return string "08090a0b"

var a = new Uint8Array(4);
function pad(str ) {
return str.length < 2 ? "0" + str : str;
}
[].map.call( a, function(v) {
return pad(v.toString(16));
}).join(""); //00000000

Related

Converting a 64 bit HEX to Decimal Floating-Pointt in Javascript

So basically I have a couple of numbers that come out as HEX values in the form of "3FF0000000000000" and I want to get float values of out these, pretty much like in here So in this particular case I'd expect "20.000000000000000" as a result - which I'll later trim to only 5 decimals, but that should be easy enough.
I've tried a couple of solutions but unfortunately I know too little about conversions (and javascript aswell) to know exactly what I might be doing wrong.
The latest try looks something like this:
const hexToFloat64 = (hex) => {
var int32 = [],
float64;
if (hex.length > 4) {
var high = hex.substr(0, 8),
low = hex.substr(8, 8);
int32.push(parseInt(high, 16), parseInt(low, 16));
}
var uint32 = new Uint32Array(int32);
float64 = new Float64Array(uint32.buffer);
var returnValue = float64[0];
return returnValue;
};
Much obliged!
This is NOT an answer to your exact problem. It IS a solution to decode the hex. Thats all i am doing here. I have no context to solve your problem.
function convHexStringToString(ss) {
// ss length must be even (or 0) when passed to this function
var s = "";
var p;
if (ss.length > 0) {
if (ss.length % 2 == 0) {
var l = Math.floor(ss.length / 2); // floor must never have to do work
for (var i = 0; i < l; i++) {
var i2 = i * 2;
if (ss.charAt(i2) != "0") {
p = ss.charAt(i2) + ss.charAt((i2) + 1);
}
else {
p = ss.charAt((i2) + 1);
}
d = parseInt(p,16);
s += String.fromCharCode(d);
}
}
}
return s;
}

Node Red javascript Convert a HEX string to a ACSII string [duplicate]

How to convert from Hex string to ASCII string in JavaScript?
Ex:
32343630 it will be 2460
function hex2a(hexx) {
var hex = hexx.toString();//force conversion
var str = '';
for (var i = 0; i < hex.length; i += 2)
str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
return str;
}
hex2a('32343630'); // returns '2460'
Another way to do it (if you use Node.js):
var input = '32343630';
const output = Buffer.from(input, 'hex');
log(input + " -> " + output); // Result: 32343630 -> 2460
For completeness sake the reverse function:
function a2hex(str) {
var arr = [];
for (var i = 0, l = str.length; i < l; i ++) {
var hex = Number(str.charCodeAt(i)).toString(16);
arr.push(hex);
}
return arr.join('');
}
a2hex('2460'); //returns 32343630
You can use this..
var asciiVal = "32343630".match(/.{1,2}/g).map(function(v){
return String.fromCharCode(parseInt(v, 16));
}).join('');
document.write(asciiVal);
** for Hexa to String**
let input = '32343630';
Note : let output = new Buffer(input, 'hex'); // this is deprecated
let buf = Buffer.from(input, "hex");
let data = buf.toString("utf8");
I found a useful function present in web3 library.
var hexString = "0x1231ac"
string strValue = web3.toAscii(hexString)
Update: Newer version of web3 has this function in utils
The functions now resides in utils:
var hexString = "0x1231ac"
string strValue = web3.utils.hexToAscii(hexString)
I've found that the above solution will not work if you have to deal with control characters like 02 (STX) or 03 (ETX), anything under 10 will be read as a single digit and throw off everything after. I ran into this problem trying to parse through serial communications. So, I first took the hex string received and put it in a buffer object then converted the hex string into an array of the strings like so:
buf = Buffer.from(data, 'hex');
l = Buffer.byteLength(buf,'hex');
for (i=0; i<l; i++){
char = buf.toString('hex', i, i+1);
msgArray.push(char);
}
Then .join it
message = msgArray.join('');
then I created a hexToAscii function just like in #Delan Azabani's answer above...
function hexToAscii(str){
hexString = str;
strOut = '';
for (x = 0; x < hexString.length; x += 2) {
strOut += String.fromCharCode(parseInt(hexString.substr(x, 2), 16));
}
return strOut;
}
then called the hexToAscii function on 'message'
message = hexToAscii(message);
This approach also allowed me to iterate through the array and slice into the different parts of the transmission using the control characters so I could then deal with only the part of the data I wanted.
Hope this helps someone else!
console.log(
"68656c6c6f20776f726c6421".match(/.{1,2}/g).reduce((acc,char)=>acc+String.fromCharCode(parseInt(char, 16)),"")
)
An optimized version of the implementation of the reverse function proposed by #michieljoris (according to the comments of #Beterraba and #Mala):
function a2hex(str) {
var hex = '';
for (var i = 0, l = str.length; i < l; i++) {
var hexx = Number(str.charCodeAt(i)).toString(16);
hex += (hexx.length > 1 && hexx || '0' + hexx);
}
return hex;
}
alert(a2hex('2460')); // display 32343630
I use this one, it seems more clear to me as I also receive data with spaces like '30 31 38 30 38 30' and the output is 018080
hexToString(hex: string): string {
return hex.split(' ').map(s => string.fromCharCode(parseInt(s,16))).join('');
}

How to alternate the case of a string

I'm working on alternating the case of a string (for example asdfghjkl to AsDfGhJkL).
I tried to do this. I found some code that is supposed to do it, but it doesn't seem to be working.
var str="";
var txt=document.getElementById('input').value;
for (var i=0; i<txt.length; i+2){
str = str.concat(String.fromCharCode(txt.charCodeAt(i).toUpperCase()));
}
Here's a quick function to do it. It makes the entire string lowercase and then iterates through the string with a step of 2 to make every other character uppercase.
var alternateCase = function (s) {
var chars = s.toLowerCase().split("");
for (var i = 0; i < chars.length; i += 2) {
chars[i] = chars[i].toUpperCase();
}
return chars.join("");
};
var txt = "hello world";
console.log(alternateCase(txt));
HeLlO WoRlD
The reason it converts the string to an array is to make the individual characters easier to manipulate (i.e. no need for String.prototype.concat()).
Here an ES6 approach:
function swapCase(text) {
return text.split('').map((c,i) =>
i % 2 == 0 ? c.toLowerCase() : c.toUpperCase()
).join('');
}
console.log(swapCase("test"))
You should iterate the string and alternate between upper-casing the character and lower-casing it:
for (var i=0; i<txt.length; i++) {
var ch = String.fromCharCode(txt.charCodeAt(i);
if (i % 2 == 1) {
ch = ch.toUpperCase();
} else {
ch = ch.toLowerCase();
}
str = str.concat(ch);
}

how to get formatted integer value in javascript

This is my integer value
12232445
and i need to get like this.
12,232,445
Using prototype how to get this?
var number = 12232445,
value = number.toString(),
parts = new Array;
while (value.length) {
parts.unshift(value.substr(-3));
value = value.substr(0, value.length - 3);
}
number = parts.join(',');
alert(number); // 12,232,445
It might not be the cleanest solution, but it'll do:
function addCommas(n)
{
var str = String(n);
var result = '';
for(var i = 0; i < str.length; i++)
{
if((i - str.length) % 3 == 0)
result += ',';
result += str[i];
}
return result;
}
Here is the function I use, to format thousands separators and takes into account decimals if any:
function thousands(s) {
var rx = /(-?\d+)(\d{3})/,
intDec = (''+s)
.replace(new RegExp('\\' + $b.localisation.thousandSeparator,'g'), '')
.split('\\' + $b.user.localisation.decimalFormat),
intPart = intDec[0],
decPart = intDec[1] || '';
while (rx.test(intPart)) {
intPart = intPart.replace(rx,'$1'+$b.localisation.thousandSeparator+'$2');
}
return intPart + (decPart && $b.localisation.decimalFormat) + decPart;
}
thousands(1234.56) //--> 1,234.56
$b.localisation is a global variable used for the session.
$b.localisation.thousands can have the values , or . or a space.
And $b.localisation.decimalFormat can have the values , or . depending on the locale of the user

How to convert from Hex to ASCII in JavaScript?

How to convert from Hex string to ASCII string in JavaScript?
Ex:
32343630 it will be 2460
function hex2a(hexx) {
var hex = hexx.toString();//force conversion
var str = '';
for (var i = 0; i < hex.length; i += 2)
str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
return str;
}
hex2a('32343630'); // returns '2460'
Another way to do it (if you use Node.js):
var input = '32343630';
const output = Buffer.from(input, 'hex');
log(input + " -> " + output); // Result: 32343630 -> 2460
For completeness sake the reverse function:
function a2hex(str) {
var arr = [];
for (var i = 0, l = str.length; i < l; i ++) {
var hex = Number(str.charCodeAt(i)).toString(16);
arr.push(hex);
}
return arr.join('');
}
a2hex('2460'); //returns 32343630
You can use this..
var asciiVal = "32343630".match(/.{1,2}/g).map(function(v){
return String.fromCharCode(parseInt(v, 16));
}).join('');
document.write(asciiVal);
** for Hexa to String**
let input = '32343630';
Note : let output = new Buffer(input, 'hex'); // this is deprecated
let buf = Buffer.from(input, "hex");
let data = buf.toString("utf8");
I found a useful function present in web3 library.
var hexString = "0x1231ac"
string strValue = web3.toAscii(hexString)
Update: Newer version of web3 has this function in utils
The functions now resides in utils:
var hexString = "0x1231ac"
string strValue = web3.utils.hexToAscii(hexString)
I've found that the above solution will not work if you have to deal with control characters like 02 (STX) or 03 (ETX), anything under 10 will be read as a single digit and throw off everything after. I ran into this problem trying to parse through serial communications. So, I first took the hex string received and put it in a buffer object then converted the hex string into an array of the strings like so:
buf = Buffer.from(data, 'hex');
l = Buffer.byteLength(buf,'hex');
for (i=0; i<l; i++){
char = buf.toString('hex', i, i+1);
msgArray.push(char);
}
Then .join it
message = msgArray.join('');
then I created a hexToAscii function just like in #Delan Azabani's answer above...
function hexToAscii(str){
hexString = str;
strOut = '';
for (x = 0; x < hexString.length; x += 2) {
strOut += String.fromCharCode(parseInt(hexString.substr(x, 2), 16));
}
return strOut;
}
then called the hexToAscii function on 'message'
message = hexToAscii(message);
This approach also allowed me to iterate through the array and slice into the different parts of the transmission using the control characters so I could then deal with only the part of the data I wanted.
Hope this helps someone else!
console.log(
"68656c6c6f20776f726c6421".match(/.{1,2}/g).reduce((acc,char)=>acc+String.fromCharCode(parseInt(char, 16)),"")
)
An optimized version of the implementation of the reverse function proposed by #michieljoris (according to the comments of #Beterraba and #Mala):
function a2hex(str) {
var hex = '';
for (var i = 0, l = str.length; i < l; i++) {
var hexx = Number(str.charCodeAt(i)).toString(16);
hex += (hexx.length > 1 && hexx || '0' + hexx);
}
return hex;
}
alert(a2hex('2460')); // display 32343630
I use this one, it seems more clear to me as I also receive data with spaces like '30 31 38 30 38 30' and the output is 018080
hexToString(hex: string): string {
return hex.split(' ').map(s => string.fromCharCode(parseInt(s,16))).join('');
}

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