converting hexadecimal escape chars to binary

Question

I'm looking for a way to uniformly convert JavaScript chars to binary. One problem that I'm facing is that I'm not able to convert strings used in unescape function correctly

document.write("HI"); ==> HI (case 1)
document.write("\x48\x49");  ==> HI (case 2)
document.write(unescape("%48%49")); ==> HI (case 3)

Case 1: Converting "HI" to binary generates:

0100100001001001

Case 2: Converting "\x48\x49" to binary generates:

0100100001001001

Case 3: Converting "%48%49" to binary generates:

001001010011010000111000001001010011010000111001

I understand what is happening in case 3. it converts each char to binary without realizing that these chars are in hex representation. I'm wondering if there is a way to make case 3 have the same binary representation as case 1 and case 2 without any pre-processing required?

I.e, is there a function either in JavaScript, Python or any other language that can realize that "%48" is one char represented in hex and is able to convert it to binary?

You are only using Javascript here, so why did you add the Java and Python tags? Javascript isn't Java at all. It is another language. — , Jun 27 '16 at 11:25
I'm interested in converting chars in JavaScript code to binary. As for the conversion process, I'm open to use any programming language the is able to convert the above 3 cases uniformly — user5289027, Jun 27 '16 at 11:33

score 0 · Accepted Answer · answered Jun 27 '16 at 11:23

0

The decodeURIComponent is the right function for this. The decode function is deprecated. Here is an example.

If you put %48%49 in the input and click on the 'Convert' button, it gives you the second case.

var test = document.querySelector("#test");
var btn = document.querySelector("#btn");
var result = document.querySelector("#result");

btn.addEventListener("click", function() {
  var value = decodeURIComponent(test.value);
  var resultText = "";
  
  for (i = 0; i < value.length; i++) {
    resultText += value.charCodeAt(i).toString(2);
  }
  
  result.innerText = resultText;
});

<input type="text" id="test">
<button id="btn">Convert</button>

<p id="result"></p>

answered Jun 27 '16 at 11:23

but this can't handle case 2 correctly. It returns 1011100111100011010011100010111001111000110100111001 for "\x48\x49" – user5289027 Jun 27 '16 at 11:57
Yes but this is because when you type `"\x48\x49"`, it transforms at compile time. You can try this in your browser console: type `"\x48\x49"`and it will return "HI" without any other function call. The snippet is just an example to tell you that you should use the `decodeURIComponent` function for what you are trying to achieve. If you want to get HI at runtime you can use the eval function but it is very dangerous. – Jun 27 '16 at 12:29
@user5289027 check out [How do I un-escape a backslash-escaped string in python?](http://stackoverflow.com/questions/1885181/how-do-i-un-escape-a-backslash-escaped-string-in-python) for the second case. – Tadhg McDonald-Jensen Jun 27 '16 at 17:18

converting hexadecimal escape chars to binary

1 Answers1