getting all locally defined objects in javascript module

Question

I have this code:

<script type="module">
  const _Tasks = {};
  const _client = {};
  const _client_simple = {};
  const _status = {};
  const _status_simple = {};
  
  //need here a function to get all above declared and defined objects in a loop

</script>

I am trying to get all the above declared and defined objects in a loop.

I have tried this way:

  const objects = Object.getOwnPropertyNames(this);
  objects.forEach(objectName => {
    console.log(objectName);
  });

But this is undefined.

Is this possible and how?

Variables defined with `const` and `let` cannot be (directly) accessed by any other means than their name. if you use `var` in the global scope, you can access it with `window.yourVarName`. — Samathingamajig, Feb 03 '23 at 09:52
as far as I can say things defined in a module are contained and won't be accessible if not imported explicitely. Since `this` makes sense only in the execution context and since the caller has to import explicitely the objects it wants to use in its execution context, you should know upfront the variables you are going to export — Diego D, Feb 03 '23 at 10:01

score 3 · Answer 1 · answered Feb 03 '23 at 10:01

JavaScript provides no mechanisms for determining what variables exist.

If you need to programmatically inspect a group of data, then you need to express that data as a group in the first place (e.g. as properties of an object that you can iterate through) instead of as individual variables.

If, on the other hand, this is just for debugging purposes, then pausing execution in the module (e.g. with a breakpoint) will cause most debugging tools to display the variables in scope.

score 1 · Answer 2 · answered Feb 03 '23 at 19:22

Short answer: JavaScript has no concept of querying the list of variables defined as const or let.

You can however query the list of variables defined with var because they are attached to the window object. This is the windowKeys example below.

If you want to query the variables why not adding them to an object? This is the myObjectKeys example below.

var _Tasks = {};
var _client = {};
var _client_simple = {};
var _a_number = 123;
var _a_string = "hello";
var _a_boolean = true;

const windowKeys = Object.keys(window).filter(key => /^_/.test(key));
console.log('windowKeys:');
windowKeys.forEach(key => {
  console.log('  ' + key + ', type: ' + typeof window[key]);
});

const myObject = {
  _Tasks: {},
  _client: {},
  _client_simple: {},
  _a_number: 123,
  _a_string: "hello",
  _a_boolean: true
}
const myObjectKeys = Object.keys(myObject);
console.log('myObjectKeys:');
windowKeys.forEach(key => {
  console.log('  ' + key + ', type: ' + typeof myObject[key]);
});

Output:

windowKeys:
  _Tasks, type: object
  _client, type: object
  _client_simple, type: object
  _a_number, type: number
  _a_string, type: string
  _a_boolean, type: boolean
myObjectKeys:
  _Tasks, type: object
  _client, type: object
  _client_simple, type: object
  _a_number, type: number
  _a_string, type: string
  _a_boolean, type: boolean

getting all locally defined objects in javascript module

2 Answers2