function askForJSON(path) {
  // create panel
  let panel = NSOpenPanel.openPanel()

  // set panel properties
  panel.setTitle('Select JSON')
  panel.setMessage("Please select the JSON file you'd like to use.")
  panel.setPrompt('Select')
  panel.setCanCreateDirectories(false)
  panel.setCanChooseFiles(true)
  panel.setCanChooseDirectories(false)
  panel.setAllowsMultipleSelection(false)
  panel.setShowsHiddenFiles(false)
  panel.setExtensionHidden(false)
  panel.setAllowedFileTypes(['json'])

  // set initial panel path
  if (path) {
    panel.setDirectoryURL(NSURL.fileURLWithPath(path))
  } else {
    panel.setDirectoryURL(NSURL.fileURLWithPath('/Users/' + NSUserName()))
  }

  // show panel
  let pressedButton = panel.runModal()
  if (pressedButton === NSOKButton) {
    return panel.URL().path()
  }
}
Prompts user to select the JSON file and returns the path of the file.

@param {String} path - Path to set for the file browser.
@returns {String}