Unhandled rejection TypeError: path.extname is not a function

Question

I am trying to write a function that goes trough the content of a directory and returns all the xml files inside the directory. So far I am able to return all the files in the directory (console.log(files) prints out an array of strings with the file names, but when I try to filter with the path.extname function I am getting:

usr/local/Cellar/node/6.8.0/bin/node /Users/shooshte/Sportradar/notThatKindOfPeon/bluebird.js Unhandled rejection TypeError: path.extname is not a function at /Users/shooshte/Sportradar/notThatKindOfPeon/bluebird.js:23:31 at Array.filter (native) at /Users/shooshte/Sportradar/notThatKindOfPeon/bluebird.js:22:30 at tryCatcher (/Users/shooshte/Sportradar/notThatKindOfPeon/node_modules/bluebird/js/release/util.js:16:23) at Promise._settlePromiseFromHandler (/Users/shooshte/Sportradar/notThatKindOfPeon/node_modules/bluebird/js/release/promise.js:510:31) at Promise._settlePromise (/Users/shooshte/Sportradar/notThatKindOfPeon/node_modules/bluebird/js/release/promise.js:567:18) at Promise._settlePromise0 (/Users/shooshte/Sportradar/notThatKindOfPeon/node_modules/bluebird/js/release/promise.js:612:10) at Promise._settlePromises (/Users/shooshte/Sportradar/notThatKindOfPeon/node_modules/bluebird/js/release/promise.js:691:18) at Promise._fulfill (/Users/shooshte/Sportradar/notThatKindOfPeon/node_modules/bluebird/js/release/promise.js:636:18) at /Users/shooshte/Sportradar/notThatKindOfPeon/node_modules/bluebird/js/release/nodeback.js:42:21 at FSReqWrap.oncomplete (fs.js:123:15)

This is my code:

const Promise = require('bluebird');
const fs = Promise.promisifyAll(require('fs'));
const path = require('path');

function getFileNames(path) {
  // Read content of path
  return fs.readdirAsync(path)
      // For every file in path
      .then(function(content) {
        // Filter out the directories
        return content.filter(function(file) {
          return fs.statSync(path + '/' + file).isDirectory();
        });
      })
      // For every directory
      .then(function(directories) {
        directories.map(function(directory) {
          // Read file in the directory
          fs.readdirAsync(path + '/' + directory + '/')
              .then(function(files) {
                // Filter out the XMLS
                return files.filter(function(file) {
                  return path.extname(file) == '.XML';
                });
                console.log(files);
              });
          });
        });
      }

getFileNames('./XML');

Answer 1

You're using path for two different things, and they're interfering with each other. You have a module global:

const path = require('path');
// ---^

...but then you shadow that with an argument:

function getFileNames(path) {
// -------------------^

So within getFileNames, the path identifier refers to that argument, not your global, and since it doesn't refer to the path module (from context, I'm guessing the path argument is a string), you don't have path.extname.

Use different names.