How to ignore escape characters in javascript?

Question

I have the following string:

var str = '\x27';

I have no control on it, so I cannot write it as '\\x27' for example. Whenever I print it, i get:

since 27 is the apostrophe. When I call .length on it, it gives me 1. This is of course correct, but how can I treat it like a not escaped string and have it print literally

\x27

and give me a length of 4?

Duplicate : http://stackoverflow.com/questions/6184453/how-to-make-javascript-ignore-escape-character — Vishal Kamal, Dec 11 '15 at 12:22
No it's not. The proposed solution in that question is "You need to escape the backslash, i.e., use \\ instead of just \:" and I explicitly stated right in the second line of my question that I cannot do that, so it's a different question for a different context. — pistacchio, Dec 11 '15 at 12:25
Why do you need to do this? - `str` is `'` and nothing else, it does not matter how it was assigned to. If you want to print 4 you would need to apply a logical test; `len = str == "'" ? 4 : str.length` - Or are you asking how to derive an escape sequence form a char? — Alex K., Dec 11 '15 at 12:28
So given `var a = "'", b = "\x27";` you want a way to determine that `b` exists in the source as an escape sequence as opposed to a literal? — Alex K., Dec 11 '15 at 12:42
No, given a = "\x27" I want to treat it as a four chars string starting with a '\', followed by an 'x' and '2' and '7, not like "'". — pistacchio, Dec 11 '15 at 13:05
The only way to do this would be to parse them out of the source code itself with a regex, the escape sequence string simply does not exist at runtime — Alex K., Dec 11 '15 at 13:10

score 1 · Answer 1 · answered Dec 11 '15 at 12:36

1

I'm not sure if you should do what you are trying to do, but this is how it works:

var s = '\x27';
var sEncoded = '\\x' + s.charCodeAt(0).toString(16);

s is a string that contains one character, the apostrophe. The character code as a hexadecimal number is 27.

answered Dec 11 '15 at 12:36

lex82

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Doesn't this work only for this specific use case? What if you don't know the contents of the variable holding the string, but still need to escape characters. – Andrew Feb 25 '23 at 23:20
@Andrew Yes, the solution shown only solves this particular problem. But of course you can generalize it and replace all the characters in the string with their char codes in a loop. – lex82 Feb 27 '23 at 09:51

score 0 · Answer 2 · edited Mar 20 '17 at 10:29

After the assignment var str = '\x27';, you can't tell where the contents of str came from. There's no way to find out whether a string literal was assigned, or whether the string literal contained an escape sequence. All you have is a string containing a single apostrophe character (Unicode code point U+0027). The original assignment could have been

var str = '\x27'; // or
var str = "'"; // or
var str = String.fromCodePoint(3 * 13);

There's simply no way to tell.

That said, your question looks like an XY problem. Why are you trying to print \x27 in the first place?

How to ignore escape characters in javascript?

2 Answers2