[JAVASCRIPT] How to use generated client?

Description

I'm getting used to Swagger, so I've created a sample API via editor and generated javascript-client code. README.md tells me to execute the following code in browser:

var PistacheTest = require('pistache_test');
var api = new PistacheTest.CalcApi()
var number1 = 789; // {Number} 1st number
var number2 = 789; // {Number} 2nd number
var callback = function(error, data, response) {
  if (error) {
    console.error(error);
  } else {
    console.log('API called successfully.');
  }
};
api.calcPost(number1, number2, callback);

Since I see require keyword, it means Node.JS, not browser javascript. Okay, I installed browserify (npm install -g browserify) and got bundle.js as browserify index.js -o bundle.js.
Then I included bundle.js as <script type="text/javascript" src="bundle.js"></script> in my test HTML webpage.

But the question is: How can I execute any functions from that bundle.js?
I tried:
var api = PistacheTest.EchoApi();
var api = PistacheTest.Echo();
var api = PistacheTest;
etc.
I see no way to execute my API calls from browser. At this point I think writing Python script which executes my API endpoints will be faster and more convenient than dealing with non-working Javascript code, which was generated by Swagger.

Swagger-codegen version

2.4.0-SNAPSHOT

Swagger declaration file content or url

https://gist.github.com/MasterGroosha/6e4ed847a53ba170273d41c5bea5c003

Command line used for generation

sudo docker run -u 1000:1000 -rm -v $(PWD):/local swaggerapi/swagger-codegen-cli generate -i /local/swagger.json -l javascript -o /local/out/code

Related issues/PRs

I don't see anything related, maybe because of my inexperience in JS/NodeJS.

Suggest a fix/enhancement

Pls help :(

Start with the generated README.md example, the generated index.js, and the browserify command described in the issue. Check whether the JavaScript client documents or supports browser use and how its exports are exposed. Done means reproducing the usage problem and either clarifying the supported invocation or identifying a concrete generator change.