Introduction to JavaScript in Postman

What is JavaScript
JavaScript is a popular programming language used to make web pages interactive and dynamic. It is widely used for:
   ● Creating interactive websites
   ● Handling user actions
   ● Sending and receiving data from APIs
   ● Automating tasks
   ● Validating data
JavaScript works in browsers as well as tools like .

Why JavaScript is Used in Postman
In , JavaScript is used to automate API testing and request handling.
JavaScript helps users to:
   ● Set dynamic request data
   ● Store and reuse values
   ● Validate API responses
   ● Automate workflows
   ● Perform calculations before sending requests
   ● Write test cases
This script stores a value inside an environment variable.

Postman Scripting Overview
Postman provides scripting features that allow users to execute JavaScript code during API execution.
Scripts are mainly used for:
   ● Automation
   ● API testing
   ● Data extraction
   ● Request chaining
Postman uses the pm API object for scripting.
These methods help interact with:
   ● Responses
   ● Variables
   ● Collections
   ● Environments

Pre-request Script vs Tests Tab
1. Pre-request Script
The Pre-request Script runs before the API request is sent.
It is used for:
   ● Generating tokens
   ● Creating dynamic timestamps
   ● Setting variables
   ● Preparing request data

2. Test Tab
The Tests script runs after receiving the API response.
It is used for:
   ● Validating response status
   ● Checking response data
   ● Writing test cases
   ● Extracting values from responses

Console Usage (console.log)
The console.log() function is used to print messages in the Postman Console.
It helps in:
   ● Debugging scripts
   ● Checking variable values
   ● Viewing execution flow
You can open the Postman Console from:
   ● View > Show Postman Console
This prints the complete API response in the console.

let name = 'Raj';
console.log(name);


let is used to create a variable
'Raj' is the value stored in the variable
console.log() prints the output to the console

let currentTime = new Date().toISOString();
pm.environment.set('time', currentTime);

pm.test('Status code is 200', function () {
    pm.response.to.have.status(200);
});

let username = 'admin';
console.log(username);

Output:

admin

let response = pm.response.json();
console.log(response);

Feature		Pre-request Script	Tests
----------------------------------------------------
Execution Time	Before request		After response
Main Purpose	Prepare request		Validate response
Common Usage	Tokens, variables	Assertions, validations

Summary:
JavaScript in helps automate API testing and scripting tasks. Using JavaScript in Pre-request Scripts and Tests makes API workflows faster, reusable, and efficient. The console.log() function is very useful for debugging and understanding script execution.