# Regular Expression

• regex-test
• learn-regex
• regexlearn
• es6-regexp

# The Basic

• left to right
• case-sensitive
• Demo
  • for john_doe,jo-hn_doe
  • BUT It does not match Jo ( uppercase, too short)
• Basic Matchers

"the" => The fat cat sat on the mat
"The" => The fat cat sat on the mat
".ar" => The car parked in the garage

# Meta Characters

• building blocks of regular expressions
• written inside brackets

Meta character	Description
.	Period matches any single character except a line break (换行符)
[ ]	Character class. Matches any character contained between the square brackets
[^ ]	Negated character class. Matches any character that is not contained between the square brackets
*	Matches 0 or more repetitions of the preceding symbol
+	Matches 1 or more repetitions of the preceding symbol
?	Makes the preceding symbol optional
{n,m}	Braces. Matches at least "n" but not more than "m" repetitions of the preceding symbol
(xyz)	Character group. Matches the characters xyz in that exact order
|	Alternation. Matches either the characters before or the characters after the symbol
\	Escapes (转义) the next character. This allows you to match reserved characters [ ] ( ) { } . * + ? ^ $ \ |
^	Matches the beginning of the input
$	Matches the end of the input