annatorok / exam-web-2016-07-25

Caesar Cipher

Create a web-app, that is able to decode encoded text with Ceasar Cipher.

It should have one page consisting several things:

• A text area to place the encrypted text
• A number input to specify the shift
• A paragraph to display the decoded message
• A button to send the the request and display the decoded message

The decryption should be done by a backend service:

• It should serve the html for the page
• It should have a POST endpoint on the path: /decode
  • It should expect an object as post data like:

  {
    "shift": 3,
    "text": "oruhp lsvxp groru vlw"
  }

• It should response with something like this (with 200 status):

  {
    "status": "ok",
    "text": "lorem ipsum dolor sit"
  }

• It should accept shift number between -25 and 25
• It should only translate the the real letters (a-z and A-Z) (you can use the /[a-zA-Z]/ RegExp)
• If any of the properties are missing of the post data or the shift is out of bound it should response an error like (with 400 status):

  {
    "status": "error",
    "error": "Shift is out of bound"
  }

Other requirements:

• The program should write loading till the XHR request is pending
• If the input is invalid it should alert the user
• The decryption unit should be in a separate file and it should be unit tested (it should not consist any express related code)