Last signature is missing when multiple are defined

Search terms

• signature
• missing

Expected Behavior

If I scan a method with multiple signatures, then I expect all of them to be present in the typedoc.json/reflection data.

Actual Behavior

The last one is always missing. I need that at least for the default value.

Steps to reproduce the bug

export class SignatureTest {
  /**
   * Test with multiple signatures.
   *
   * @param a The value to return.
   */
  multiSignature(a: boolean): boolean;
  multiSignature(a: number): number;
  multiSignature(a: unknown = 1): unknown {
    return a;
  }
}

typedoc.json

{
	"id": 0,
	"name": "@faker-js/faker",
	"kind": 1,
	"kindString": "Project",
	"flags": {},
	"originalName": "",
	"children": [
		{
			"id": 1,
			"name": "SignatureTest",
			"kind": 128,
			"kindString": "Class",
			"flags": {},
			"children": [
[...]
				{
					"id": 4,
					"name": "multiSignature",
					"kind": 2048,
					"kindString": "Method",
					"flags": {},
					"sources": [...]
					"signatures": [
						{
							"id": 5,
							"name": "multiSignature",
							"kind": 4096,
							"kindString": "Call signature",
							"flags": {},
							"comment": {
								"shortText": "Test with multiple signatures."
							},
							"parameters": [
								{
									"id": 6,
									"name": "a",
									"kind": 32768,
									"kindString": "Parameter",
									"flags": {},
									"comment": {
										"shortText": "The value to return.\n"
									},
									"type": {
										"type": "intrinsic",
										"name": "boolean"
									}
								}
							],
							"type": {
								"type": "intrinsic",
								"name": "boolean"
							}
						},
						{
							"id": 7,
							"name": "multiSignature",
							"kind": 4096,
							"kindString": "Call signature",
							"flags": {},
							"parameters": [
								{
									"id": 8,
									"name": "a",
									"kind": 32768,
									"kindString": "Parameter",
									"flags": {},
									"type": {
										"type": "intrinsic",
										"name": "number"
									}
								}
							],
							"type": {
								"type": "intrinsic",
								"name": "number"
							}
						},
+						{
+							"id": 9,
+							"name": "multiSignature",
+							"kind": 4096,
+							"kindString": "Call signature",
+							"flags": {},
+							"parameters": [
+								{
+									"id": 10,
+									"name": "a",
+									"kind": 32768,
+									"kindString": "Parameter",
+									"flags": {},
+									"type": {
+										"type": "intrinsic",
+										"name": "unknown"
+									},
+									"defaultValue": "1"
+								}
+							],
+							"type": {
+								"type": "intrinsic",
+								"name": "unknown"
+							}
+						}
					]
				}
			],
[...]
		}
	],
[...]
}

Environment

• Typedoc version: ~0.22.12
• TypeScript version: ~4.6.2
• Node.js version: v16.14.0
• OS: Windows 11
• Related:
  • #1879 - Jsdocs comments only present on first signature

[Gerrit0]

What would be the best way to get the complete default value from the implementation signature?

That’s going to depend on what you mean by “complete”. Default values are an arbitrary expression, there’s no guarantee that they are a simple value… so it really depends on your use case. The simplest way to do this is, of course, to just get the text from the source file. This will put the default parameters in the JSON as strings from the source file, or null if a parameter doesn’t have a default value.

// typedoc --plugin path/to/this/file.js
const td = require("typedoc");

/** @param {td.Application} app */
exports.load = function (app) {
    app.converter.on(
        td.Converter.EVENT_CREATE_DECLARATION,
        /**
         * @param {td.Context} context
         * @param {td.Reflection} reflection
         */
        (context, reflection) => {
            const symbol = context.project.getSymbolFromReflection(reflection);
            if (!symbol) return;

            if (
                reflection.kindOf(td.ReflectionKind.Function | td.ReflectionKind.Method) &&
                (symbol.declarations?.length ?? 0) > 1
            ) {
                const lastDeclaration = symbol.declarations[symbol.declarations.length - 1];
                if (td.TypeScript.isFunctionLike(lastDeclaration)) {
                    reflection.implementationDefaultParameters = lastDeclaration.parameters.map(
                        (param) => param.initializer?.getText() || null
                    );
                    console.log(reflection.implementationDefaultParameters);
                }
            }
        }
    );

    // So that it shows up in JSON output
    app.serializer.addSerializer({
        serializeGroup(item) {
            return item instanceof td.Reflection;
        },
        supports(item) {
            return true;
        },
        toObject(refl, obj) {
            obj.implementationDefaultParameters = refl.implementationDefaultParameters;
            return obj;
        },
    });
};

[ST-DDT]

Thanks for this example. I added this to our project in https://github.com/faker-js/faker/pull/656