Cool tricks with ES6 templated strings

example.js

import {p} from './get-path';

console.log(p`${'userDesktop'}/MyApp`);

// On Windows
>> C:\Users\TheUser\Desktop\MyApp

// On OS X
>> /Users/TheUser/Desktop/MyApp

console.log(p`${'HOME'}/Downloads`)

// On Windows
>> C:\Users\TheUser\Downloads

// On OS X
>> /Users/TheUser/Downloads

get-path.js

import _ from 'lodash';
import path from 'path';

let electronApp = null;
if (process.type === 'renderer') {
  electronApp = require('remote').require('app');
} else {
  electronApp = require('app');
}

// NB: Some environment variables are known to app.getPath and we don't have 
// to worry about them disappearing on us. Use them instead.
const environmentVariableAliases = {
  'HOME': 'home',
  'USERPROFILE': 'home',
  'APPDATA': 'appData',
  'TEMP': 'temp',
  'TMPDIR': 'temp'
};

const pathCache = { };

export function getPath(key) {
  if (pathCache[key]) return pathCache[key];
  
  let aliasKey = null;
  if (environmentVariableAliases[key]) {
    aliasKey = environmentVariableAliases[key];
  }
  
  let result = null;
  try {
    result = electronApp.getPath(aliasKey || key);
  } catch (e) {
    console.log(e);
  }
  
  result = result || process.env[key];
  if (!result) {
    // NB: Try to fix up the most commonly fucked environment variables
    if (key.toLowerCase() === 'appdata' && process.env.USERPROFILE) {
      result = path.join(process.env.USERPROFILE, 'AppData', 'Roaming');
    }
    
    if (key.toLowerCase() === 'localappdata' && process.env.USERPROFILE) {
      result = path.join(process.env.USERPROFILE, 'AppData', 'Local');
    }
  }
 
  if (result) pathCache[key] = result;
  return result;
}

export function p(strings, ...values) {
  let newVals = _.map(values, (x) => getPath(x));
  let newPath = String.raw(strings, ...newVals);
  let parts = _.map(newPath.split(/[\\\/]/), (x) => x || '/');
  
  try {
    return path.resolve(...parts);
  } catch (e) {
    return path.join(...parts);
  }
}