JavaScript regular expression basics and practice

• Chapter1 Basic knowledge of regular expressions
• 1-1 First experience with regular expressions
• 1-2 Two ways to create regular objects
• 1-3 What are regular modifiers?
• 1-4 Types and uses of atomic characters
• 1-5 mysterious metacharacters
• 1-6 Character object methods that support regular parameters
• Chapter2 Regular expression practical case
• 2-1 Use capture groups to get the most repeated characters and their number (1)
• 2-2 Use capture groups to get the most repeated characters and their number (2)
• 2-3 How to remove whitespace characters in the middle and sides of a string
• 2-4 How to verify whether the email is legitimate?
• 2-5 How to filter mobile phone numbers in user messages?