There are a number of metacharacters that require special treatment when trying to match them. To match these special characters, you must first escape those characters, that is, precede them with a backslash character (\). The following table shows those special characters and their meanings:
| Special Character | Comment |
|---|---|
| $ | Matches the position at the end of an input string. If the RegExp object's Multiline property is set, $ also matches the position preceding '\n' or '\r'. To match the $ character itself, use \$. |
| ( ) | Marks the beginning and end of a subexpression. Subexpressions can be captured for later use. To match these characters, use \( and \). |
| * | Matches the preceding subexpression zero or more times. To match the * character, use \*. |
| + | Matches the preceding subexpression one or more times. To match the + character, use \+. |
| . | Matches any single character except the newline character \n. To match ., use \. |
| [ | Marks the beginning of a bracket expression. To match [, use \[. |
| ? | Matches the preceding subexpression zero or one time, or indicates a non-greedy quantifier. To match the ? character, use \?. |
| \ | Marks the next character as either a special character, a literal, a backreference, or an octal escape. For example, 'n' matches the character 'n'. '\n' matches a newline character. The sequence '\\' matches "\" and '\(' matches "(". |
| ^ | Matches the position at the beginning of an input string except when used in a bracket expression where it negates the character set. To match the ^ character itself, use \^. |
| { | Marks the beginning of a quantifier expression. To match {, use \{. |
| | | Indicates a choice between two items. To match |, use \|. |