get extension from a file name

Author: aladin002dz

L-B/0026 FileExtension/FileExtension.js

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+function extractFileExtension(fileName) {
+    // Split the file name into an array of strings at the dot character.
+    const splitFileName = fileName.split('.');
+
+    // Check if the split file name array has more than one element.
+    if (splitFileName.length > 1) {
+        // Get the last element in the array, which is the file extension.
+        const fileExtension = splitFileName.pop();
+
+        // Return the file extension.
+        return fileExtension;
+    }
+    // The file name does not have an extension, so return an empty string.
+    return '';
+}
+
+module.exports = extractFileExtension;

L-B/0026 FileExtension/FileExtension.test.js

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+
+const extractFileExtension = require('./FileExtension')
+
+describe('extractFileExtension', () => {
+    it('should return the file extension when given a valid file name', () => {
+        expect(extractFileExtension('example.txt')).toBe('txt');
+        expect(extractFileExtension('document.docx')).toBe('docx');
+        expect(extractFileExtension('image.jpg')).toBe('jpg');
+    });
+
+    it('should return an empty string when given a file name without an extension', () => {
+        expect(extractFileExtension('README')).toBe('');
+        expect(extractFileExtension('LICENSE')).toBe('');
+    });
+
+    it('should return an empty string when given an empty string', () => {
+        expect(extractFileExtension('')).toBe('');
+    });
+});
+
+/*
+test output:
+ PASS  ./FileExtension.test.js
+  extractFileExtension
+    √ should return the file extension when given a valid file name (4 ms)
+    √ should return an empty string when given a file name without an extension (1 ms)
+    √ should return an empty string when given an empty string
+
+Test Suites: 1 passed, 1 total
+Tests:       3 passed, 3 total
+Snapshots:   0 total
+Time:        0.958 s, estimated 1 s
+Ran all test suites.
+*/
+
+/*
+Testing with Jest global installation:
+> npm install -g jest
+> jest
+*/

L-B/0026 FileExtension/README.md

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+# Get the file extension
+
+## Problem
+
+Write a function that takes a string and returns the file extension, which is the string after the last dot (.) in the string. If there is no dot in the string, return undefined.
+
+## Solution
+
+```javascript
+function extractFileExtension(fileName) {
+  // Split the file name into an array of strings at the dot character.
+  const splitFileName = fileName.split(".");
+
+  // Get the last element in the array, which is the file extension.
+  const fileExtension = splitFileName.pop();
+
+  // Return the file extension.
+  return fileExtension;
+}
+```
+
+## How it works
+
+- The `extractFileExtension` function takes a string as an argument.
+- The `split` method is used to split the string into an array of strings at the dot character.
+- The `pop` method is used to get the last element in the array, which is the file extension.
+- The file extension is returned.
+
+## References
+
+- [String.prototype.split()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/split)
+
+## Problem Added By
+
+- [GitHub](https://github.com/aladin002dz)
+
+## Contributing
+
+Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.
+
+Please make sure to update tests as appropriate.

L-B/0026 FileExtension/jest.config.json

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+{}