swagger-jsdoc setup in Express - Step-by-Step Execution

Concept Flow - swagger-jsdoc setup

Import swagger-jsdoc

↓

Define swagger options

↓

Generate swaggerSpec with swagger-jsdoc

↓

Use swaggerSpec in Express app

↓

Serve Swagger UI with generated docs

This flow shows how to import swagger-jsdoc, define options, generate docs, and serve them in an Express app.

Execution Sample

Express

const swaggerJSDoc = require('swagger-jsdoc');

const options = {
  definition: { openapi: '3.0.0', info: { title: 'API', version: '1.0.0' } },
  apis: ['./routes/*.js']
};

const swaggerSpec = swaggerJSDoc(options);

This code imports swagger-jsdoc, sets options with API info and files, then generates the swaggerSpec object.

Execution Table

Step	Action	Input/State	Output/State
1	Import swagger-jsdoc	None	swaggerJSDoc function available
2	Define options object	Set openapi version, info, apis path	options object created
3	Call swaggerJSDoc(options)	options object	swaggerSpec object generated with API docs
4	Use swaggerSpec in Express	swaggerSpec object	Swagger UI can serve API docs
5	Serve Swagger UI route	Express app configured	API docs accessible at /api-docs

💡 Swagger docs are ready and served in Express app

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
swaggerJSDoc	undefined	function imported	function imported	function imported
options	undefined	{definition, apis}	{definition, apis}	{definition, apis}
swaggerSpec	undefined	undefined	generated swaggerSpec object	generated swaggerSpec object

Key Moments - 3 Insights

Why do we need to specify the 'apis' path in options?

The 'apis' path tells swagger-jsdoc where to find the API route files with comments to generate docs, as shown in step 2 of the execution_table.

What does swagger-jsdoc(options) return?

It returns a swaggerSpec object containing the OpenAPI documentation generated from the options and API comments, as seen in step 3.

How do we make the generated docs visible in the Express app?

By using the swaggerSpec object with a Swagger UI middleware route in Express, as described in steps 4 and 5.

Visual Quiz - 3 Questions

Look at the execution_table, what is the output after step 3?

A swagger-jsdoc function imported

B options object with API paths

C swaggerSpec object with API docs

D Express app configured

💡 Hint

Check the 'Output/State' column for step 3 in execution_table

At which step do we define the API info like title and version?

A Step 2

B Step 1

C Step 3

D Step 4

💡 Hint

Look at the 'Action' and 'Input/State' columns in execution_table for where options are created

If we change the 'apis' path in options, what changes in the execution?

A swagger-jsdoc function will not import

B swaggerSpec will include docs from new API files

C Express app will crash

D No change in swaggerSpec

💡 Hint

Refer to the role of 'apis' in step 2 and 3 of execution_table

Concept Snapshot

swagger-jsdoc setup:
1. Import swagger-jsdoc
2. Define options with OpenAPI info and API file paths
3. Generate swaggerSpec by calling swaggerJSDoc(options)
4. Use swaggerSpec in Express to serve docs
5. Access docs via Swagger UI route

Full Transcript

This visual execution shows how to set up swagger-jsdoc in an Express app. First, you import the swagger-jsdoc library. Then, you create an options object that includes OpenAPI version, API information like title and version, and the paths to your API route files. Next, you call swaggerJSDoc with these options to generate a swaggerSpec object containing your API documentation. Finally, you use this swaggerSpec in your Express app to serve the Swagger UI, making your API docs accessible to users. The execution table traces each step, showing how variables change and how the setup progresses until the docs are ready to serve.