s/[\s|\t]//g;
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If the  \t in the  [\s|\t] character set had been some non-redundant, non-whitespace character and thus not subject to removal, a potential problem would have remained. The  | (pipe) character in the set is a literal '|', not the regex alternation metacharacter, so the set would have contained an extraneous character – perhaps the basis of a subtle bug. A regex character set implies alternation.