1. Regular expressions
RegExp Tester: for text responses only
When testing with regular expressions, you must master regular expressions
Learning path: https://www.runoob.com/regexp/regexp-syntax.html
2. Obtaining method
a. Ordinary acquisition: use square brackets: [baiji]
b. Acquisition of special characters: <title>(.*)</title>: *, simply means to represent any string
| ( ) | Marks the start and end of a subexpression. Subexpressions can be retrieved for later use. To match these characters, use \( and \). |
Start with <title> and end with </title>
| * | Matches the preceding subexpression zero or more times. To match * characters, use \*. |
| . | Matches any single character except newline \n. To match ., use \.. |
| ? | Matches the preceding subexpression zero or one time, or specifies a non-greedy qualifier. To match a ? character, use \?. |
