NativeScript/nativescript-core/globals/ts-helpers.ts

// Required by V8 snapshot generator
if (!global.__extends) {
  global.__extends = function (d, b) {
    for (let p in b) {
      if (b.hasOwnProperty(p)) {
        d[p] = b[p];
      }
    }
    function __() {
      this.constructor = d;
    }
    d.prototype = b === null ? Object.create(b) : ((__.prototype = b.prototype), new __());
  };
}

import * as tslib from 'tslib';

// Bind the tslib helpers to global scope.
// This is needed when we don't use importHelpers, which
// breaks extending native-classes
for (const fnName of Object.keys(tslib)) {
  if (typeof tslib[fnName] !== 'function') {
    continue;
  }

  if (fnName in global) {
    // Don't override globals that are already defined (ex. __extends)
    continue;
  }

  global[fnName] = tslib[fnName];
}