Function shouldUseNative

docs/tests/v2/es6/js/sanddance.js:7563–7609

()

}

function shouldUseNative() {
  try {
    if (!Object.assign) {
      return false;
    } // Detect buggy property enumeration order in older V8 versions.
    // https://bugs.chromium.org/p/v8/issues/detail?id=4118


    var test1 = new String('abc'); // eslint-disable-line no-new-wrappers

    test1[5] = 'de';

    if (Object.getOwnPropertyNames(test1)[0] === '5') {
      return false;
    } // https://bugs.chromium.org/p/v8/issues/detail?id=3056


    var test2 = {};

    for (var i = 0; i < 10; i++) {
      test2['_' + String.fromCharCode(i)] = i;
    }

    var order2 = Object.getOwnPropertyNames(test2).map(function (n) {
      return test2[n];
    });

    if (order2.join('') !== '0123456789') {
      return false;
    } // https://bugs.chromium.org/p/v8/issues/detail?id=3056


    var test3 = {};
    'abcdefghijklmnopqrst'.split('').forEach(function (letter) {
      test3[letter] = letter;
    });

    if (Object.keys(Object.assign({}, test3)).join('') !== 'abcdefghijklmnopqrst') {
      return false;
    }

    return true;
  } catch (err) {
    // We don't expect any of the above to throw, but better to be safe.
    return false;
  }
}

module.exports = shouldUseNative() ? Object.assign : function (target, source) {
  var from;