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queryObjects - node__v8.d.ts - Node documentation
function queryObjects
Unstable

Usage in Deno

```typescript import { queryObjects } from "node:node__v8.d.ts"; ```
queryObjects(ctor: Function): number | string[]
This is similar to the [`queryObjects()` console API](https://developer.chrome.com/docs/devtools/console/utilities#queryObjects-function) provided by the Chromium DevTools console. It can be used to search for objects that have the matching constructor on its prototype chain in the heap after a full garbage collection, which can be useful for memory leak regression tests. To avoid surprising results, users should avoid using this API on constructors whose implementation they don't control, or on constructors that can be invoked by other parties in the application. To avoid accidental leaks, this API does not return raw references to the objects found. By default, it returns the count of the objects found. If `options.format` is `'summary'`, it returns an array containing brief string representations for each object. The visibility provided in this API is similar to what the heap snapshot provides, while users can save the cost of serialization and parsing and directly filter the target objects during the search. Only objects created in the current execution context are included in the results. ```js import { queryObjects } from 'node:v8'; class A { foo = 'bar'; } console.log(queryObjects(A)); // 0 const a = new A(); console.log(queryObjects(A)); // 1 // [ "A { foo: 'bar' }" ] console.log(queryObjects(A, { format: 'summary' })); class B extends A { bar = 'qux'; } const b = new B(); console.log(queryObjects(B)); // 1 // [ "B { foo: 'bar', bar: 'qux' }" ] console.log(queryObjects(B, { format: 'summary' })); // Note that, when there are child classes inheriting from a constructor, // the constructor also shows up in the prototype chain of the child // classes's prototoype, so the child classes's prototoype would also be // included in the result. console.log(queryObjects(A)); // 3 // [ "B { foo: 'bar', bar: 'qux' }", 'A {}', "A { foo: 'bar' }" ] console.log(queryObjects(A, { format: 'summary' })); ```

Parameters

ctor: Function
The constructor that can be used to search on the prototype chain in order to filter target objects in the heap.

Return Type

number | string[]
queryObjects(
ctor: Function,
options: { format: "count"; },
): number

Parameters

ctor: Function
options: { format: "count"; }

Return Type

number
queryObjects(
ctor: Function,
options: { format: "summary"; },
): string[]

Parameters

ctor: Function
options: { format: "summary"; }

Return Type

string[]