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How to Document an Express API with Swagger UI and JSDoc

Kate Bartolo on November 29, 2020

JSDoc is a popular tool for generating documentation from comments in the source code of your app. This serves two purposes. First, the documentati...

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hkhattabii • Nov 29 '20

It is possible to generate the documentation into a static html page to be readeable without launching the server ?

Kate Bartolo • Nov 29 '20

Good question! I'll look into this and get back to you

hkhattabii • Nov 30 '20

Thank you very much :)

Kate Bartolo • Nov 30 '20

No problem. It looks like Rolf's answer is the way to go. Good luck :)

hkhattabii • Nov 30 '20

I seen that what he shared is for a maven project and I try to find for an express project :(

Kate Bartolo • Nov 30 '20 • Edited

Oh okay, I think I found a way to generate an HTML file. I'm not really familiar with Swagger Codegen, but I found this wrapper: swagger-nodegen-cli. This makes it easier to install.

You have to have Java installed, then just run

npm install -g swagger-nodegen-cli

Try running sc version to make sure it was installed correctly.

Assuming you want to write the docs using JSDoc, you can generate a swagger.json spec file with swagger-jsdoc:

Install swagger-jsdoc globally:

npm install -g swagger-jsdoc

In the root directory of your Express project, create a separate file for the Swagger definition object (swaggerDefinition from the tutorial):

// swagger-def.js
module.exports = {
  openapi: '3.0.0',
  info: {
    title: 'Express API for JSONPlaceholder',
    version: '1.0.0',
    description:
      'This is a REST API application made with Express. It retrieves data from JSONPlaceholder.',
    license: {
      name: 'Licensed Under MIT',
      url: 'https://spdx.org/licenses/MIT.html',
    },
    contact: {
      name: 'JSONPlaceholder',
      url: 'https://jsonplaceholder.typicode.com',
    },
  },
  servers: [
    {
      url: 'http://localhost:3000',
      description: 'Development server',
    },
  ],
};

To create the swagger.json file, run

swagger-jsdoc -d swagger-def.js routes/*.js

Replace routes/*.js with the paths to your files with JSDoc comments. Also see the swagger-jsdoc CLI docs.

These file paths are all relative to the root directory, so be sure to change them depending on where you want your files to live.

Finally, to create the HTML file, run

sc generate -i swagger.json -l html

You should have an index.html in the root directory. Let me know if this works for you!

hkhattabii • Nov 30 '20

Thank you I will try that now ! :)

Hyeonss • Jun 23 '23

If you are using Tspec, it automatically parses your TypeScript types and generates up-to-date OpenAPI specification with beautiful Swagger UI.
I strongly recommend you to try it out to make static html page with Tspec.

Rolf Streefkerk • Nov 30 '20

yes there is:
github.com/swagger-api/swagger-cod...

hkhattabii • Nov 30 '20

Thank toi, I will look forward tous afternoon :)

Rahul kumar • Feb 14 '22

Go through the source code and trigger the function/file which is being executed

pshdevio • Feb 16 '21

This might sound crazy, but the easiest way I've found is to simply Save the HTML page out from your browser once it's generated ! Crazily simple.

Shuwen • Jan 13 '21

GET /users/:id doesn't work for me. I change it to GET /users/{id}, which works.

In the api-docs, once I input id number and click execute, here is the difference:

/users/{id}
curl -X GET "localhost:3000/users/1" -H "accept: application/json"

/users/:id
curl -X GET "localhost:3000/users/:id" -H "accept: application/json"

Raphael Habereder • Jan 13 '21

Good find! And also, welcome to DEV :)

As far as I know, swagger implements {} as template delimiters, not colons, but I'm not using node a lot (yet), so maybe I am missing something here.
I can't find any information in the swagger-docs that mention the colon-style, so input from @kabartolo would be great here :)

Kate Bartolo • Jan 13 '21

Hi Shuwen!
I'm really glad you pointed this out because it's totally a bug. I'm not sure why I thought :id worked, but you're right that it doesn't.

I'll update the tutorial and sample project. Thank you!

Shuwen • Jan 13 '21

Hi Kate, Thank you your article to help me setting up my swagger documentation. One of the best article I find and I've recommend it to my coworkers.

Kate Bartolo • Jan 13 '21

Thank you so much! I'm happy it was helpful

Rolf Streefkerk • Nov 30 '20

There's another way of doing this with tools provided by Swagger.io you can have it load in the OpenAPI yaml document, and it will generate the HTML specification document for you.

github.com/swagger-api/swagger-cod...

Kate Bartolo • Nov 30 '20

This is good to know, thank you!

Mamta Shettigar • Apr 14 '21

Hi I'm using swagger-jsdoc library. Wanted to know if Visual Studio code offers any extensions for intellisense? There is an extension named swagger-jsdoc but the syntax for post request is quite outdated according to openapi 3.0.0 and hence not able to get automatic intellisense for requestBody..It still uses ;-
parameters:

- name: "param_name"
description: "매개변수"
in: body
required: true
type: string
example: "foo"

Instead of requestBody:

required: true
content:
application/json:
schema:
$ref: '#/components/schemas/NewUser'

Alexander • Jun 3 '21 • Edited

This is the main drawback of the whole swagger-jsdoc approach to swagger.
Defining API schema as an annotation to your method in the comment section is prone to typos and other mistakes that are not picked up.

I usually go to editor.swagger.io and define the whole API spec there with all the "definitions" schemas and what not. Alternatively, you could use the OpenAPI (Swagger) Editor extension for VS Code ( I don't use it though, so not sure how up-to-date it is).
Then it is a matter of copying pieces of it into right places in the code.
Also, note that you don't have to define the common definitions and schemas in the annotation section in your code. It is cleaner to put them into a separate yaml file, say definitions.yaml, then load the file directly into swaggerJSDoc object:

const options = {
  swaggerDefinition,
  // Paths to files containing OpenAPI definitions
  apis: ['./routes/*.js', './doc/definitions.yaml'],
};

burloiumarian23 • Aug 20 '23 • Edited

Good hint ... it wasn't working initially for me , because I also added anotation paths which was wrong

Hyeonss • Jun 23 '23

In 2023, you don't need to do that.

⚠️ The worst down-side of generating OpenAPI with JSDoc is REPEATING yourself for every schemas you made even if some schemas are shared with other APIs. (violating the DRY principle) ⚠️

Tspec automatically parses your TypeScript types and generates up-to-date OpenAPI specification with beautiful Swagger UI.

I strongly recommend you to try it out as I'm a maintainer of Tspec.

yeahhaey • Jun 23 '23

Nice

Gal Elmalah • Nov 29 '20

This is great!
Thank you 🙂

Kate Bartolo • Nov 29 '20

Thanks! Hope it was helpful :)

Aman Panjwani • Feb 22 '22

Hi, is there any way to specify schema in a variable form ?
eg-> using joi-tos-wagger(npmjs.com/package/joi-to-swagger).

It would be great if I can just specify swagger components schemas in the validation files itself, would save a lot of time. Or is there any other alternate available ?

PS-: currently there are some articles to use joi-to-swagger, which does the same thing, like -: medium.com/swlh/do-not-repeat-your.... But I'm asking if we can do this with jsdoc.

Thanks.

Rajitha Gunathilake • Feb 25 '21

thanks for the article
this was really helpful .👌

Shuwen • Jan 13 '21

This is the article I am looking for. Thank you!

Mitesh Kamat • Nov 30 '20

Thanks for sharing. I wasn't aware of this.

Mahbod Ahmadi • Apr 2 '22

Can we use a javascript variable in the swagger comment doc?
I have a json file and stored the responses messages and I wanna use them into doc. How can I do that?