Postman script to exract access_token from response and save it into a variable

postman_extract_access_token.js

var response = JSON.parse(pm.response.text());
var jwt = response.access_token;

pm.collectionVariables.set("access_token", jwt);

var cryptoJS = require('crypto-js')

function base64UrlDecode(base64Url) {
    let base64 = base64Url.replace(/-/g, '+').replace(/_/g, '/');
    switch (base64.length % 4) {
        case 2: base64 += '=='; break;
        case 3: base64 += '='; break;
    }
    return cryptoJS.enc.Base64.parse(base64).toString(cryptoJS.enc.Utf8);
}

function decodeJWT(token) {
    try {
        const parts = token.split('.');
        if (parts.length !== 3) {
            throw new Error('Invalid token');
        }

        const header = JSON.parse(base64UrlDecode(parts[0]));
        const payload = JSON.parse(base64UrlDecode(parts[1]));
        const signature = parts[2];

        console.log('Header:', JSON.stringify(header, null, 2));
        console.log('Payload:', JSON.stringify(payload, null, 2));
        console.log('Signature:', signature);
    } catch (error) {
        console.error('Error decoding token:', error);
    }
}

decodeJWT(jwt);