How is that JSON.parse() is able to parse to JS Object without actually having the Object Propery defined in the JSON endpoint?

Question

I'm working with the below code.

• I'm trying to reach a JSON file, and fetch some data.
• Pass it to render() function and convert to Javascript Object.

Promise.all(STATUS_CODES.map((status) => {
  const url = `https://${domainName}/api/v2/search/tickets?query="status:${status}"`;
  return client.request.get(url, options);
})).then((responses) => { render(responses); }) // [1] Function invoked here
  .catch((err) => { 
  showError('API request(s) failed.');
  console.error('API request(s) failed.', err);
});
}

function render(responses) {
  /** Convert JSON String into Javascript Object */
  const data = responses.map(r => JSON.parse(r.response)); // [2] Confused with this line
  const max = Math.max(...data.map(d => d.total));

The problem that I need help with is in this line

const data = responses.map(r => JSON.parse(r.response));

Here is some data that I fetch the JSON at ${status} = 2 : https://codebeautify.org/online-json-editor/cb535226

Problem

When [1] is invoked, and the JSON string is sent as a parameter to [2] to parse in JS Object. But, in the statement r.response , I expect there has to be a response property in the JSON. But I'm not able to find it if I manually search for it.

However in the next line d.total , I'm able to find total property.

The Complete code works just as fine as expected, but I want to understand how does it work if response property is not there in the JSON String?

Answer 1

It sounds like client.request.get(url, options) returns a Promise that resolves to an object which has a .response property. responses is an array of those objects , not an array of JSON strings.

In other words, each JSON response is wrapped inside another object, and accessing the .response property on one of those objects gives you access to the actual response data (which, here, is a JSON string).

The wrapper object (in your code, it's called r ) may contain other data like the URL requested, or the status code of the response. The .response property is not part of the JSON - it's part of the client.request.get interface.