Get the Part After Last Occurrence in a String in JavaScript or Node.js

JavaScript’s stdlib for strings contains dozens of methods. These methods are useful in a lot of situations. Yet, there are use cases where a method doesn’t exist in the stdlib.

For situations where you want to retrieve the part of a string after the last occurrence of a given character sequence, you need to build your own utility function. That’s what this tutorial shows you: how to build your own afterLast string utility method.

Node.js Series Overview

  1. String Replace All Appearances
  2. Remove All Whitespace From a String in JavaScript
  3. Generate a Random ID or String in Node.js or JavaScript
  4. Remove Extra Spaces From a String in JavaScript or Node.js
  5. Remove Numbers From a String in JavaScript or Node.js
  6. Get the Part Before a Character in a String in JavaScript or Node.js
  7. Get the Part After a Character in a String in JavaScript or Node.js
  8. How to Check if a Value is a String in JavaScript or Node.js
  9. Check If a String Includes All Strings in JavaScript/Node.js/TypeScript
  10. Check if a Value is a String in JavaScript and Node.js
  11. Limit and Truncate a String to a Given Length in JavaScript and Node.js
  12. Split a String into a List of Characters in JavaScript and Node.js
  13. How to Generage a UUID in Node.js
  14. Reverse a String in JavaScript or Node.js
  15. Split a String into a List of Lines in JavaScript or Node.js
  16. Split a String into a List of Words in JavaScript or Node.js
  17. Detect if a String is in camelCase Format in Javascript or Node.js
  18. Check If a String Is in Lowercase in JavaScript or Node.js
  19. Check If a String is in Uppercase in JavaScript or Node.js
  20. Get the Part After First Occurrence in a String in JavaScript or Node.js
  21. Get the Part Before First Occurrence in a String in JavaScript or Node.js
  22. Get the Part Before Last Occurrence in a String in JavaScript or Node.js
  23. Get the Part After Last Occurrence in a String in JavaScript or Node.js
  24. How to Count Words in a File
  25. How to Shuffle the Characters of a String in JavaScript or Node.js
  26. Append Characters or Words to a String in JavaScript or Node.js
  27. Check if a String is Empty in JavaScript or Node.js
  28. Ensure a String Ends with a Given Character in JavaScript or Node.js
  29. Left-Trim Characters Off a String in JavaScript or Node.js
  30. Right-Trim Characters Off a String in JavaScript or Node.js
  31. Lowercase the First Character of a String in JavaScript or Node.js
  32. Uppercase the First Character of a String in JavaScript or Node.js
  33. Prepend Characters or Words to a String in JavaScript or Node.js
  34. Check if a String is a Number
  35. Convert a String to Buffer
  36. Prevent Line Breaks in String Template Literals
  37. How to Implement a Custom `toString` Method (Coming soon)
  38. What Is `Symbol.toStringTag` and How to Use It (Coming soon)

Retrieve the String Part After the Last Delimiter Occurrence

JavaScript comes with the String#split method. This split method divides a given string value at each occurrence of a given delimiter. The result is an array of ordered substrings.

The afterLast utility should return the last item in the array of substrings. In case the divided array of substrings contains only one item, it means the delimiter value wasn’t found and you’re returning the original string value.

Here’s a sample afterLast utility function returning the part of a string after the last occurrence of a given character:

/**
 * Returns the portion of the string after the last occurrence of the given `delimiter`.
 *
 * @param {String} delimiter
 *
 * @returns {String}
 */
function afterLast (value, delimiter) {  
  value = value || ''

  return delimiter === ''
      ? value
      : value.split(delimiter).pop()
}

Notice: splitting a string for an empty delimiter creates an array of the string’s characters. That’s why you need to return the original value when receiving an empty string as a delimiter.

Then you can use the afterLast function like this:

afterLast('Future Studio is an awesome island', 'is')  
// 'land'

afterLast('Future Studio is an awesome island', 'great')  
// 'Future Studio is an awesome island'

afterLast('Future Studio')  
// 'Future Studio'

Use the @supercharge/strings Package

I’m the maintainer of the @supercharge/strings package providing convenient string utilities. It provides a useful Str#afterLast method returning the remainder of the string after the last occurrence of a given character or character sequence:

const Str = require('@supercharge/strings')

Str('Future Studio is an awesome island').afterLast('is')  
// 'land'

Str('Future Studio is an awesome island').afterLast('great')  
// 'Future Studio is an awesome island'

Str('Future Studio').afterLast()  
// 'Future Studio'

That’s it!


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