Determine if a word or phrase is an isogram.

An isogram (also known as a "nonpattern word") is a word or phrase without a repeating letter, however spaces and hyphens are allowed to appear multiple times.

Examples of isograms:

• lumberjacks
• background
• downstream
• six-year-old

The word isograms, however, is not an isogram, because the s repeats.

Go through the setup instructions for Javascript to install the necessary dependencies:

https://exercism.io/tracks/javascript/installation

Install assignment dependencies:

$ npm install

Execute the tests with:

$ npm test

In the test suites all tests but the first have been skipped.

Once you get a test passing, you can enable the next one by changing xtest to test.

Wikipedia https://en.wikipedia.org/wiki/Isogram

It's possible to submit an incomplete solution so you can see how others have completed the exercise.