FxaProductButton.fetchTokens = function()

in media/js/base/fxa-product-button.es6.js [37:98]
42 lines of code
8 McCabe index (conditional complexity)

FxaProductButton.fetchTokens = function (buttons) {
    // assume the first button should dictate the metrics flow request
    const buttonURL = buttons[0].getAttribute('href');
    let metricsURL = buttons[0].getAttribute('data-action') + 'metrics-flow';

    // strip url to everything after `?`
    const buttonURLParams = buttonURL.match(/\?(.*)/)[1];

    // collect values from Fxa product button
    const params = window._SearchParams.queryStringToObject(buttonURLParams);

    // add required params to the token fetch request
    metricsURL += '?form_type=' + params.form_type;

    // add service identifier for VPN (issue #10811)
    if (params.service) {
        metricsURL += '&service=' + params.service;
    }

    metricsURL += '&entrypoint=' + params.entrypoint;
    metricsURL += '&utm_source=' + params.utm_source;

    // add optional utm params to the token fetch request
    if (params.utm_campaign) {
        metricsURL += '&utm_campaign=' + params.utm_campaign;
    }

    if (params.utm_content) {
        metricsURL += '&utm_content=' + params.utm_content;
    }

    if (params.utm_medium) {
        metricsURL += '&utm_medium=' + params.utm_medium;
    }

    if (params.utm_term) {
        metricsURL += '&utm_term=' + params.utm_term;
    }

    if (params.entrypoint_experiment) {
        metricsURL += '&entrypoint_experiment=' + params.entrypoint_experiment;
    }

    if (params.entrypoint_variation) {
        metricsURL += '&entrypoint_variation=' + params.entrypoint_variation;
    }

    return fetch(metricsURL)
        .then((resp) => {
            return resp.json();
        })
        .then((r) => {
            // add retrieved deviceID, flowBeginTime and flowId values to cta url
            let flowParams = '&device_id=' + r.deviceId;
            flowParams += '&flow_begin_time=' + r.flowBeginTime;
            flowParams += '&flow_id=' + r.flowId;
            return flowParams;
        })
        .catch(() => {
            // silently fail: deviceId, flowBeginTime, flowId are not added to url.
        });
};