JavaScript libraries

Postman comes with a few built-in libraries. If you prefer to add additioal JavaScript libraries, please take a look at the Custom libraries section.

Built-in JavaScript libraries

cheerio

Simple library for working with the DOM model. Useful if you are getting back HTML.

responseHTML = cheerio(pm.response.text());
console.log(responseHTML.find('[name="firstName"]').val());

Example fetching a CSRF code form the meta tag:

const $ = cheerio.load('<meta name="csrf" Content="the code">');
console.log($("meta[name='csrf']").attr("content"));

Read more: https://github.com/cheeriojs/cheerio

Moment.js

Moment.js is already built into Postman and can make your life easier if you are working with dates.

Here is a basic usage example:

const moment = require('moment');
moment('2021-08-15').add(1, 'days').format('DD.MM.YYYY')

This script will parse a date, will add one day and will reformat the date.

Read more: https://momentjs.com/docs

crypto-js

Library which implements different crypto functions.

Hash string using SHA256

CryptoJS.SHA256("some string").toString()

HMAC-SHA1 encryption

CryptoJS.HmacSHA1("Message", "Key").toString()

AES Encryption

const encryptedText = CryptoJS.AES.encrypt('message', 'secret').toString();

AES Decryption

const plainText = CryptoJS.AES.decrypt(encryptedText, 'secret').toString(CryptoJS.enc.Utf8);

Read more: https://www.npmjs.com/package/crypto-js

Node.js libraries

NodeJS modules that are available inside Postman:

• path
• assert
• buffer
• util
• url
• punycode
• querystring
• string_decoder
• stream
• timers
• events

Custom libraries

There is no standard way of including 3rd party JavaScript libraries.

Currently the only way is to fetch (and optionally store) the content of the JavaScript library and to use the JavaScript eval function to execute the code.

Template:

pm.sendRequest("https://example.com/your-script.js", (error, response) => {
    if (error || response.code !== 200) {
        pm.expect.fail('Could not load external library');
    }

    eval(response.text());

    // YOUR CODE HERE
});

Example loading a library using unpkg as a CDN:

pm.sendRequest("https://unpkg.com/papaparse@5.1.0/papaparse.min.js", (error, response) => {
    if (error || response.code !== 200) {
        pm.expect.fail('Could not load external library');
    }

    eval(response.text());

    const csv = `id,name\n1,John`;
    const data = this.Papa.parse(csv); // notice the this
    console.log(data);
});

Notice: in order to load a library and use it in Postman, the JavaScript code needs to be “compiled” and ready for distribution. Usually the code will be available as a *.min.js file or within the dist or umd folder.