lodash.get alternative that covers _most_ cases.

lodash-get.js

// Graciously stolen from lodash's stringToPath
const charCodeOfDot = '.'.charCodeAt(0)
const reEscapeChar = /\\(\\)?/g
const rePropName = RegExp(
  // Match anything that isn't a dot or bracket.
  '[^.[\\]]+' + '|' +
  // Or match property names within brackets.
  '\\[(?:' +
    // Match a non-string expression.
    '([^"\'][^[]*)' + '|' +
    // Or match strings (supports escaping characters).
    '(["\'])((?:(?!\\2)[^\\\\]|\\\\.)*?)\\2' +
  ')\\]'+ '|' +
  // Or match "" as the space between consecutive dots or empty brackets.
  '(?=(?:\\.|\\[\\])(?:\\.|\\[\\]|$))'
  , 'g')

/**
 * Converts `string` to a property path array.
 *
 * @private
 * @param {string} string The string to convert.
 * @returns {Array} Returns the property path array.
 */
const stringToPath = (string) => {
  const result = []
  if (string.charCodeAt(0) === charCodeOfDot) {
    result.push('')
  }
  string.replace(rePropName, (match, expression, quote, subString) => {
    let key = match
    if (quote) {
      key = subString.replace(reEscapeChar, '$1')
    }
    else if (expression) {
      key = expression.trim()
    }
    result.push(key)
  })
  return result
}

/**
 * Recursively iterates over an object or array to find a nested path.
 *
 * @param {object|array} input
 * @param {string} path A dot-notation path
 * @returns {any|undefined} If a truthy value is found at the path, it is returned
 */
const get = (input, path) => {
  const pathComponents = stringToPath(path)
  const currentProp = pathComponents[0]
  // end of the road?
  if(pathComponents.length === 1) return input[currentProp]
  // keep going
  if(input[currentProp]) return get(input[currentProp], pathComponents.slice(1).join('.'))
  // surrender to the endless void
  return undefined
}