The object the widget reads once, the moment its script runs. Write it before the script tag. [`SubblyCart.initialize(config)`](/reference/cart-widget/methods#initialize) takes the same object. Only `apiKey` is required. Your Storefront API key, from the Subbly admin under Settings, Developers. A missing key throws `Missing required apiKey config`. API the widget calls. Default `https://api.subbly.co/storefront/v1/`. An empty string falls back to the default. Page-integration settings: which links the widget catches, which element opens it, which element shows the item count. Every key is on [Settings keys](#settings). Default `{}`. Two-letter language of the widget. Without it, the widget takes the `lang` query parameter of the page, then the `lang` attribute of ``, then the browser's language, and keeps the first two characters. Start from a cart you already know. Default the `subbly_cart_id` cookie. Sign a customer in at start-up. A valid token is written to the `subbly_access_token` cookie. Default that cookie. `false` stops the automatic start-up; you then call [`SubblyCart.initialize`](/reference/cart-widget/methods#initialize) yourself. Only the exact value `false` does this. Default `true`. Name of the global that gets the instance. A value that is not a non-empty string is ignored. Default `subblyCart`. A Subbly.js client you already built. The widget uses it instead of creating its own. Standalone checkout. The widget opens full screen and configures the item from `window.subblyCheckout.payload` at once. Default `false`. Page on your site that owns the checkout. The widget sends the customer there instead of opening its own, and stands down on that path. It accepts `/checkout` and `/checkout/{cartId}`; a bare page gets the current cart ID appended on redirect. Page on your site that owns the cart summary. Same behaviour as `checkoutUrl`. Paths on which the widget stands down. Default `checkoutUrl` (without its cart ID) and `cartSummaryUrl`; an empty array keeps that default. Only the pathname is matched, case-insensitively. `*` matches inside one segment, `**` across segments. An entry without a wildcard also matches on a segment boundary, so `/checkout` covers `/checkout/success` but not `/checkout-foo`. ```html title="A full config object" ``` Page-integration settings. They tie the widget to the markup on your own page: which links it catches, which element opens it, which element shows the item count. Set them in `window.subblyConfig` before the script runs, or pass them to `SubblyCart.initialize()`. These are not the theme settings. Colours, typography and checkout behaviour live in the shop's cart settings, which you override with [`setSettings`](/reference/cart-widget/methods#set-settings). Catch clicks on Subbly buy links anywhere on the page, cancel the navigation, and open the widget instead. See [Sell from your own links](/developer-resources/cart-widget/wire-it-into-your-page#sell-from-your-own-links). Default `false`. Before the widget finishes loading, a stub handler cancels these clicks. It does not remember them, so a click that early is dropped. Show the widget's own floating cart button. Default `false`. The button is suppressed when the page already holds an `a.subbly-cart` element. URL of an image for the floating cart button, in place of the built-in icon. It works only with `cartButton: true`. Default `null`; anything that is not a string is ignored. CSS selector or element that opens and closes the widget. The default click action is cancelled. Clicks are caught on `document`, so elements added later still work. Default `''`. CSS selector or element whose content the widget replaces with the number of active items. It updates on `CART_READY` and `CART_UPDATED`, and after a `popstate` event, where it waits up to 5 seconds for the element and then 300 ms more before writing. Default `''`. The widget also listens for a `pushstate` event, but nothing fires one: its own patch of `history.pushState` dispatches `locationchange` instead. On a framework that routes with `pushState`, update the element yourself from `CART_UPDATED`. Show the currency and language picker in the widget header. Default `false`. Hide the cart summary and use the checkout as the first view. Default `false`. The `?disableSummaryView=1` query parameter does the same. Hide the products inside a bundle, in the summary and at the checkout. Default `false`. The `?hideBundleItems=1` query parameter does the same. ```html title="Configure the widget" ``` Query parameters the widget reads from the page URL when it starts. They make a plain link enough to drive the widget — a campaign link that applies a coupon, a referral link, a translated landing page. Four of them are used once and then remembered as used: `gift`, `coupon`, `r` and `custom_setup_return_url`. A bank confirmation that sends the customer back to the same URL does not apply them twice. Language of the widget, when `languageCode` is not in the config. The widget takes the first two characters. Coupon code to hold and apply once the cart fits it, as [`setPendingCoupon`](/reference/cart-widget/methods#set-pending-coupon) does. Used once. Any value opens the gift view. Used once. ID of the referring customer. Used once. Prefills the checkout email. `customerEmail` is a deprecated fallback. Prefills the first name. Prefills the last name. Prefills the marketing opt-in. Prefills the terms checkbox. Your own ID for the customer. It is stored on the customer profile. Any value hides the summary and uses the checkout as the first view. Any value hides the products inside a bundle. URL of your own receipt page, in place of the widget's. URL the customer returns to after a Stripe 3-D Secure check. Used once. `test` runs the checkout in test mode. Set by Stripe on the return redirect. `payment_method_id` and `redirect_status` come with it. ```html title="A campaign link" 10% off your first box ```