Using Scripts

Resonance runs JavaScript before a request is sent (pre-request scripts) and after the response arrives (test scripts). Scripts run in a sandboxed engine embedded in the app — no data leaves your machine unless a script calls sendRequest.

Overview

• Write scripts in the Scripts tab of the request panel, in the Pre-request or Test sub-tab — they save automatically
• Console output, test results and errors appear in the Scripts tab of the response panel
• The collection runner runs the same scripts for every request in a run
• Scripts run synchronously, top to bottom — no setTimeout, fetch or Promises that need scheduling
• A script is stopped after 30 seconds (for example an endless loop) and reports an error

What Happens After a Script

• Pre-request: changes to request are applied to the outgoing request
• Pre-request failure: if the script throws, the request is not sent and the error is shown in its place; in the runner the request is marked failed
• Both: environment.set / unset changes are saved to the active environment, and pm.collectionVariables.set / unset changes to the request's collection

request

The outgoing request, mutable in pre-request scripts. Variables such as {{name}} are already resolved when the script runs.

request.headers["Authorization"] = `Bearer ${environment.get("token")}`;
request.queryParams["page"] = "2";
delete request.queryParams["debug"];

response (test scripts)

expect(response.status).toBe(200);
expect(response.body.user.email).toMatch(/@example\.com$/);
environment.set("userId", String(response.body.user.id));

environment

Read and write variables of the active environment. Values are strings; a value set earlier in the same script is returned by get.

const host = environment.get("host");
environment.set("requestId", "abc-123");
environment.unset("tempToken");

cookies

Read and write the cookie jar of the active environment (also pm.cookies). See Cookie Jar.

Testing

describe("user endpoint", () => {
    test("returns 200", () => {
        expect(response.status).toBe(200);
    });
    it("returns a user id", () => {
        expect(response.body.user).toHaveProperty("id");
    });
});

A failing expectation inside test / it fails that test and moves on. expect at the top level records each assertion as its own result and stops the script on failure.

sendRequest(urlOrOptions[, callback])

Makes an HTTP request from a script. It is synchronous and returns the response directly; the Postman-style callback form also works.

const res = sendRequest({
    url: environment.get("authUrl"),
    method: "POST",
    headers: { "Content-Type": "application/x-www-form-urlencoded" },
    body: "grant_type=client_credentials&client_id=" + environment.get("clientId")
});
if (res.status === 200) {
    environment.set("token", res.json().access_token);
}

• Options: url (required), method, headers, body (objects are sent as JSON), timeout in ms (default 10 000, max 60 000)
• Response: status, statusText, headers, body, json(), text()
• Network errors and timeouts throw — wrap calls in try/catch
• Redirects are followed; the app's proxy settings apply, client certificates do not

Crypto & Encoding

const signature = CryptoJS.HmacSHA256(request.body, environment.get("secret"))
    .toString(CryptoJS.enc.Base64);
request.headers["X-Signature"] = signature;

Postman Compatibility (pm)

Scripts written for Postman run largely unchanged — including scripts that come in with a Postman import.

Not supported yet: pm.execution.setNextRequest / skipRequest, pm.vault, and require for modules other than crypto-js.

Limitations

• No file system or system access; sendRequest is the only network call
• No fetch, XMLHttpRequest, import, setTimeout or browser storage
• Scripts are stopped after 30 seconds; each sendRequest has its own timeout
• Environment values are stored as strings — convert with String(…) / Number(…)

Troubleshooting

The request was not sent

• A failing pre-request script stops the send — the error is shown in the response area and the Scripts tab

Variable missing in the next request

• Make sure an environment is active before using environment.set
• Log the value with console.log(environment.get("name"))
• Check the spelling between environment.set and the {{name}} placeholder

Assertion fails unexpectedly

• Log response.status and response.body before asserting
• response.body is already an object for JSON responses — no JSON.parse needed

Next Steps

• Getting Started — request basics and environment setup
• Collection Runner — run sequences using script-captured variables
• Mock Server — test script flows against local mock endpoints