Blog post: automatic tokens for postman pre-request scripts

[james2doyle]

Use a URL that contains a JSON token value and set that dynamically per-request

pm.sendRequest({
    url: ['http://', pm.collectionVariables.get("baseUrl"), '/sanctum/csrf-cookie'].join(''),
    method: 'GET'
}, function (error, response, { cookies }) {
    if (!error && cookies) {
        pm.environment.set('xsrfToken', cookies.get('XSRF-TOKEN'))
        pm.sendRequest({
            url: ['http://', pm.collectionVariables.get("baseUrl"), '/token.json'].join(''),
            method: 'GET'
        }, function (error, response) {
            if (!error && response) {
                try {
                    pm.collectionVariables.set('authToken', response.json().token)
                } catch (err) {
                    console.error(err);
                }
            }
        })
    }
})