var x = "Test \'"
> undefined
var y = "Test '"
> undefined
x === y
> true
x
> "Test '"
https://i.stack.imgur.com/ZrHo5.jpg
Aha! Both of these strings are actually equal (as shown in the example code) - but why is that the case?
What causes this unexpected equality when escaping single quotes? Please explain.
Thanks in advance!
Showing through example code that both strings are equal, the real question is why?
It's important to note that the escape character is never actually part of the string value itself; rather, it is used by the parser to interpret the string.
The specifications detail how escape sequences are interpreted: Learn more here
https://i.stack.imgur.com/MZlaO.jpg
Interestingly, escape sequences in double quoted strings (DoubleStringCharacter) are evaluated in the same way as those in single quoted strings (SingleStringCharacter). Both evaluate \ EscapeSequence.
The use of a backslash in a string is to escape the character that follows it. When using single quotes within double quotes, there is no need to escape the single quote.
For example:
"Test \'s" === "Test 's"
'Test\"s' === 'Test"s'
Imagine a situation where you need both single and double quotes in a string. In this scenario, it is important to escape the inner quotes to avoid any errors with string formatting. By using a backslash \, the special meaning of characters can be discarded in favor of their literal interpretation.
"He said, \"My name is something, I stay at my uncle's house.\""
The values are considered identical:
Length of "Test '" is 6
Length of "Test \'" is also 6
A comprehensive list of special characters that can be used in JavaScript strings includes:
\0 \b \f \n \r \t \v \' \" \\ \XXX \xXX \uXXXX \u{XXXXX}If a character is not provided in the table, a leading backslash may be disregarded, although this practice is outdated and best avoided.
In conclusion:
JavaScript first converts the string "Test \'" to "Test '", then proceeds with comparing it to the other string "Test '".
It appears that the interpreter is automatically escaping single quotes ' due to the presence of double quotes ". As a result, it interprets the string as starting with " and allows any text within it.
The escape character \ is expected to be used before a single quote in order to produce just '. Additionally, since " is required to terminate the string, using ' within the string body will not affect this. Therefore, both strings exist in memory alike.
Test "
This explanation may only be speculation, but it seems like the most logical conclusion. The comparison a===b returns true because both strings are essentially identical. Although the inner workings of JavaScript remain unclear, other programming languages would likely have a and b referencing the same memory object.
Attempting to escape characters is futile, as the interpreter will simply disregard it.
var a = "Test \'"
var b = "Test '"
a
> "Test '"
b
> "Test '"
If you try to do this:
var a = "\a";
a
> "a"
Just like I mentioned before, any unexpected escaping will be completely ignored.
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