There are two ways to create a RegExp object: a literal notation and a constructor.
- The literal notation’s parameters are enclosed between slashes and do not use quotation marks.
- The constructor function’s parameters are not enclosed between slashes but do use quotation marks.
A regular expression is a sequence of characters that forms a search pattern. The search pattern can be used for text search and text to replace operations. A regular expression can be a single character or a more complicated pattern.
What is the regular expression?
A regular expression (sometimes called a rational expression) is a sequence of characters that define a search pattern, mainly for use in pattern matching with strings, or string matching, i.e. “find and replace”-like operations. Regular expressions are a generalized way to match patterns with sequences of characters.
What is the purpose of in regular expression?
Regular expressions are particularly useful for defining filters. Regular expressions contain a series of characters that define a pattern of text to be matched—to make a filter more specialized, or general. For example, the regular expression ^AL[.]* searches for all items beginning with AL.
How to use regular expressions to search for W3Schools?
Use a regular expression to do a case-insensitive search for “w3schools” in a string: The result in n will be: The replace () method replaces a specified value with another value in a string: let text = “Visit Microsoft!”; Use a case insensitive regular expression to replace Microsoft with W3Schools in a string:
Do you have to put regular expressions in a variable?
You don’t have to put the regular expression in a variable first. The two lines above can be shortened to one: /e/.test(“The best things in life are free!”); The exec () method is a RegExp expression method. It searches a string for a specified pattern, and returns the found text as an object.
How are flags included in a regular expression?
Regular expressions have six optional flags that allow for functionality like global and case insensitive searching. These flags can be used separately or together in any order, and are included as part of the regular expression. To include a flag with the regular expression, use this syntax: var re = / pattern / flags;