Regular expression to get a class name from html

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温柔的废话 2021-01-13 09:39

I know my question might look like a duplication for this question, but its not
I am trying to match a class name inside html text that comes from the

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臣服心动 (楼主)

2021-01-13 10:32

Using a regex, this pattern should work for you:

var r = new RegExp("(<\\w+?\\s+?class\\s*=\\s*['\"][^'\"]*?\\b)" + key + "\\b", "i");
#                   Λ                                         Λ                  Λ
#                   |_________________________________________|                  |
#                           ____________|                                        |
# [Creating a backreference]                                                     |
# [which will be accessible]  [Using "i" makes the matching "case-insensitive".]_|
# [using $1 (see examples).]  [You can omit "i" for case-sensitive matching.   ]

E.g.

var oldClass = "b";
var newClass = "e";
var r = new RegExp("..." + oldClass + "...");

"".replace(r, "$1" + newClass);
    // ^-- returns: 
"".replace(r, "$1" + newClass);
    // ^-- returns:     
"".replace(r, "$1" + newClass);
    // ^-- returns:      // <-- NO change

NOTE:
For the above regex to work there must be no ' or " inside the class string.
I.e.

 will NOT match.