What private fields, methods, or accessors does this class have?
This is possible because node, in v12.5+ as of this writing, directly exposes the v8 engine's internal debugger protocol via the core inspector
module. This should not be exposed to runtime code - it's meant for Chrome's devtools to be able to use, for debugging only. It will not work in any other environment.
Please do not use this for any non-debugging purpose. Private fields, methods, and accessors, just like closed-over variables, variable names, or function argument names, are an internal implementation detail, and they can and likely will be changed in a non-semver-major update, because by definition they are not breaking changes - since they're not observable. Consider yourself warned.
Note: this package will work down to node v8.3, but private fields support was added in node v12.0, and private methods/accessors were added in node v14.6.
Getting started
npm install --save private-fields
Usage/Examples
import getPrivateFields from 'private-fields';
import assert from 'assert';
const objectValue = { a: 1 };
const symbolValue = Symbol.iterator;
class C {
#x;
#y = 3;
#foo() {}
get #z() {}
set #z(v) {}
#object = objectValue;
#symbol = symbolValue;
}
const fields = await getPrivateFields(new C());
assert.deepEqual(fields, [
{
name: '#foo',
type: 'function',
description: '#foo() {}', // functions are not provided, but their toString is
},
{
name: '#z',
get: { type: 'function', description: 'get #z() {}' },
set: { type: 'function', description: 'set #z(v) {}' },
},
{
name: '#x',
value: undefined,
},
{
name: '#y',
value: 3,
},
{
name: '#object',
clonedValue: { a: 1 },
},
{
name: '#symbol',
clonedValue: Symbol(Symbol.iterator),
},
]);
const [, , , , object, symbol] = fields;
assert.notEqual(object, objectValue); // the original object is not provided
assert.deepEqual(object, objectValue); // but its properties are cloned
assert.notEqual(symbol.clonedValue, Symbol.iterator); // symbols are not provided
assert.equal(symbol.description, Symbol.iterator.description); // but a symbol with the same description is
Tests
Simply clone the repo, npm install
, and run npm test