JavaScript Regular Expressions

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Definitions

String - Any collection of 0 or more characters.
Example:
“This is a String”


SubString - A segment of a String
Example:
“is a”


Case Sensitivity - detection if a character is upper or lower case.


What is a Regular Expression

A regular expression is a pattern of characters.
We use regular expressions to search for matches on particular text.

How are regular expressions implemented in JavaScript??

There are two ways:
1) Using literal syntax.
var RegularExpression = /pattern/
2) When you need to dynamically construct the regular expression, by creating instances of the regular expression object, RegExp.
var RegularExpression = new RegExp("pattern");

Categories of pattern matching characters

Position matching
Character classes matching
Repetition matching
Alternation and grouping matching
Back reference matching