| d | Generate indices for substring matches. (hasIndices) | d | (not portable) |
| g | Global search. (global) | g | (not portable) |
| i | Case-insensitive search. (ignoreCase) | i | ignorecase |
| m | Allows ^ and $ to match next to newline characters. (multiline) | m | multiline |
| s | Allows . to match newline characters. (dotAll) | s | dotall |
| u | "Unicode"; treat a pattern as a sequence of Unicode code points. (unicode) | u | (not portable) |
| v | An upgrade to the u mode with more Unicode features. (unicodeSets) | v | (not portable) |
| y | Perform a "sticky" search that matches starting at the current position in the target string. (sticky) | y | (not portable) |