babel-core/lib/babel/transformation/transformers/es6/spec.symbols.js

Turn ES6 code into readable vanilla ES5 with source maps

"use strict";

var _interopRequireWildcard = function (obj) { return obj && obj.__esModule ? obj : { "default": obj }; };

exports.UnaryExpression = UnaryExpression;
exports.__esModule = true;

var t = _interopRequireWildcard(require("../../../types"));

var metadata = {
  optional: true
};

exports.metadata = metadata;

function UnaryExpression(node, parent, scope, file) {
  this.skip();

  if (node.operator === "typeof") {
    var call = t.callExpression(file.addHelper("typeof"), [node.argument]);
    if (this.get("argument").isIdentifier()) {
      var undefLiteral = t.literal("undefined");
      return t.conditionalExpression(t.binaryExpression("===", t.unaryExpression("typeof", node.argument), undefLiteral), undefLiteral, call);
    } else {
      return call;
    }
  }
}