console.log('\d' === 'd'); // true
Character 'd' is not a special character, why javascript want to slice the escape notation. It's better to keep the escape notation in my view.
When I want to fully match string-'\d' using regular expression, it just impossible! Taking the following code as an example.
console.log(RE.test('\d')); // it should log true
console.log(RE.test('d')); // it should log false
Unfortunately, you just cannot figure out a regular expression pattern.
You have no reason to escape d in a string and JavaScript ignores it. If you need \d you need to escape the escape character: \\d.
\d has a special meaning in regular expressions (a digit character), but also in strings (escaped 'd' character, which is exactly like 'd').
Any / creates an escape sequence in a string. Some are "useful" (\n === new line) and some arguably useless (`'\d' === 'd').
If you want the regex \d, you could
1 - use a regex literal instead : /\d/
2 - escape the \ in the string : '\\d', so that the string containing the two characters \ and d is correctly understood by Javascript.