Function hashKey

test/angular/1.6/angular.js:4087–4105

* Computes a hash of an 'obj'. * Hash of a: * string is string * number is number as string * object is either result of calling $$hashKey function on the object or uniquely generated id, * that is also assigned to the $$hashKey property of the object. * * @param obj * @returns {s

(obj, nextUidFn)

 *         The resulting string key is in 'type:hashKey' format.
 */
function hashKey(obj, nextUidFn) {
  var key = obj && obj.$$hashKey;

  if (key) {
    if (typeof key === 'function') {
      key = obj.$$hashKey();
    }
    return key;
  }

  var objType = typeof obj;
  if (objType === 'function' || (objType === 'object' && obj !== null)) {
    key = obj.$$hashKey = objType + ':' + (nextUidFn || nextUid)();
  } else {
    key = objType + ':' + obj;
  }

  return key;
}

// A minimal ES2015 Map implementation.
// Should be bug/feature equivalent to the native implementations of supported browsers