Pattern matching for strings that begin with the letter X and include the character Y

Question

Pattern matching for strings that begin with the letter X and include the character Y

I am in the process of creating a function to generate a regular expression that can check if a string starts with a specific sequence and contains another specified sequence.

function buildRegExp(startsWith,contains){
    return new RegExp( ????? )
}

For instance:

buildRegExp('abc','fg').test('abcdefg')

In this case, the result should be true as the string 'abcdefg' begins with 'abc' and contains 'fg'.

The 'startsWith' and 'contains' strings may overlap, so a simple search for one followed by the other will not suffice for the regular expression.

The following should also result in true:

buildRegExp('abc','bcd').test('abcdefg')

Regular expressions are necessary as I plan to use them in MongoDB queries rather than basic string operations.

javascript regex

Answer 1

Answer №1

This particular pattern is designed to effectively manage situations where the startsWith and contains substrings overlap within the string being matched:

/(?=.*bcd)^abc/

Essentially, this allows for:

return new RegExp("(?=.*" + contains + ")^" + startsWith);

Answer 2

This particular pattern is designed to effectively manage situations where the startsWith and contains substrings overlap within the string being matched:

/(?=.*bcd)^abc/

Essentially, this allows for:

return new RegExp("(?=.*" + contains + ")^" + startsWith);

Answer 3

Answer №2

Check out this regular expression pattern:

(^A).*B

For example, in Python:

import re

print(re.match(r'(a)b', 'abc')) => None

print(re.match(r'(a)b', 'abb')) => Match object

Answer 4

Check out this regular expression pattern:

(^A).*B

For example, in Python:

import re

print(re.match(r'(a)b', 'abc')) => None

print(re.match(r'(a)b', 'abb')) => Match object

Pattern matching for strings that begin with the letter X and include the character Y

Answer №1

Answer №2

Similar questions

"I'm encountering an issue with the discord.js module when I try to launch my bot using node. Any ideas on how

Creating formGroups dynamically for each object in an array and then updating the values with the object data

Javascript Snake: I am having trouble making my snake's tail grow longer

Improving JavaScript code for checking arrays and objects

Retrieve all items from the firebase database

"What is the most efficient way to break up an array into its maximum length and iterate over

Update nested child object in React without changing the original state

ReactJS incorporates multiple CSS files

What steps are involved in incorporating watchify into my gulp file?

Step-by-step guide on eliminating the modal post-validation

Tips and Tricks for Managing an Extensive Array of AJAX Requests (Exceeding 1000)

Transferring information from View to Action

Formatting dates with a DIV element

What is the technique for causing this element to move in reverse?

What is the best way to retain AJAX data even when navigating back without losing it?

Having trouble utilizing NPM package within AWS Lambda environment, encountered issue with require() function

Restrict a class to contain only functions that have a defined signature

What is the solution for handling nested promises in Node.js?

Increment the name field automatically and track the number of auto-increment variables being sent through serialization

How to retrieve multiple values from a single select dropdown form field using React