by Jeffrey Way
Lessons:26Length:1.7 hours

For full access to all 26 lessons, including source files, subscribe with Elements.
- Overview
- Transcript
4.4 Backreferences
We can use backreferences to refer to matches that we've already specified. In this example, we'll filter through a group of emails and then use a backreference to select a regular expression we've already specified.
1.Course Entrance1 lesson, 00:27
1 lesson, 00:27
Free Lesson 1.1Course Entrance00:27
Free Lesson
1.1
Course Entrance
00:27
2.Chapter 16 lessons, 30:54
6 lessons, 30:54
Free Lesson 2.1Your First Matches07:34
Free Lesson
2.1
Your First Matches
07:34
2.2Character Classes and Alternation08:42
2.2
Character Classes and Alternation
08:42
2.3Carets and Dollars05:32
2.3
Carets and Dollars
05:32
2.4Capturing Values02:44
2.4
Capturing Values
02:44
2.5Greedy Matches02:01
2.5
Greedy Matches
02:01
2.6Ranges and Curly Braces04:21
2.6
Ranges and Curly Braces
04:21
3.Chapter 24 lessons, 16:54
4 lessons, 16:54
3.1Search and Replace03:45
3.1
Search and Replace
03:45
3.2Porting the Previous Exercise to PHP03:46
3.2
Porting the Previous Exercise to PHP
03:46
3.3preg_match and preg_match_all05:41
3.3
preg_match and preg_match_all
05:41
3.4The preg_split Function03:42
3.4
The preg_split Function
03:42
4.Chapter 34 lessons, 16:42
4 lessons, 16:42
4.1Negative Lookbehinds05:29
4.1
Negative Lookbehinds
05:29
4.2Lookaheads06:13
4.2
Lookaheads
06:13
4.3Non-capturing Groups01:57
4.3
Non-capturing Groups
01:57
4.4Backreferences03:03
4.4
Backreferences
03:03
5.Chapter 46 lessons, 19:29
6 lessons, 19:29
5.1Stripping Out an Anchor Tag's Attributes02:35
5.1
Stripping Out an Anchor Tag's Attributes
02:35
5.2Matching a US Phone Number, and Named Captures03:46
5.2
Matching a US Phone Number, and Named Captures
03:46
5.3Removing Whitespace03:01
5.3
Removing Whitespace
03:01
5.4Matching an Email Address03:31
5.4
Matching an Email Address
03:31
5.5Verifying a String's Length01:52
5.5
Verifying a String's Length
01:52
5.6The Beginnings of a Markdown-like Service04:44
5.6
The Beginnings of a Markdown-like Service
04:44
6.Chapter 54 lessons, 18:13
4 lessons, 18:13
6.1An Advanced Phone Number Expression03:15
6.1
An Advanced Phone Number Expression
03:15
6.2Add Comments with the X Flag04:51
6.2
Add Comments with the X Flag
04:51
6.3Conditional Expressions (if-then)02:55
6.3
Conditional Expressions (if-then)
02:55
6.4Callback Functions for a RegEx07:12
6.4
Callback Functions for a RegEx
07:12
7.Course Exit1 lesson, 00:38
1 lesson, 00:38
7.1Course Exit00:38
7.1
Course Exit
00:38
Continue watching with Elements
Continue watching with Elements