🚀 Boosting API Testing with Pre-request and Post-response Scripts in Postman

As I’ve been working on API development and testing, I recently explored how to use Pre-request and Post-response scripts in Postman to automate and streamline my workflow. Here’s what I learned and how you can apply it too!

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🔧 Pre-request Script: Dynamic Timestamping

I needed to send a request with a timestamp that was exactly 5 hours before the current time. Here’s the script I used:

let now = new Date();
let hour = 60 * 60 * 1000;
let multiplyer = 5;

let time_iso = new Date(now.getTime() - multiplyer * hour);
pm.environment.set("time_iso", time_iso.toISOString());

✅ This script calculates the time offset and stores it in an environment variable time_iso, which I then used in the request body like this:

{
  "timestamp": "{{time_iso}}"
}

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🔐 Authorization Setup

To authenticate the request, I used a Bearer Token in the Authorization tab:

• Type: Bearer Token
• Token: {{auth_token}} (stored in environment variables)

Alternatively, you can add it manually in the Headers tab:

Key: Authorization
Value: Bearer {{auth_token}}

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🧪 Post-response Script: Status Check and Token Extraction

After the request, I wanted to validate the response and extract a token for future use. Here’s the script I used:

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

let responseData = pm.response.json();

if (responseData.token) {
    pm.environment.set("auth_token", responseData.token);
    console.log("Token saved to environment:", responseData.token);
} else {
    console.warn("Token not found in response");
}

✅ This script checks if the response was successful and saves the token to an environment variable for reuse.

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💡 Final Thoughts

Using these scripts has made my API testing more dynamic and efficient. I can now automate timestamp generation, handle authentication seamlessly, and extract data from responses without manual effort.

If you're working with APIs in Postman, I highly recommend exploring these scripting features—they’re simple to implement and incredibly powerful!