# Quick start Switch halloween.js on with body classes. A minimal example, a full example and a paste-anywhere snippet for site builders. Canonical page: https://halloween.js.org/docs/getting-started/quick-start/ halloween.js is controlled by CSS classes on ``. There is no configuration object and nothing to call. The library watches `` and reacts whenever its classes change. ## The minimal setup Load the library, then add the master class and at least one effect. ```html ... ``` This shows a spider web in the top-left corner and blinking eyes at random spots, from 18 October to 2 November. On every other day the page looks unchanged. ## What each part does - `halloween` is the [master switch](/docs/options/master-switch/). Without it nothing runs. - `halloween-screen-left-top` adds a web to a [screen corner](/docs/options/screen-corners/). - `halloween-eyes` starts an [ambient effect](/docs/options/effects/). - The [season window](/docs/options/season/) decides on which days all of this is active. ## A full example Four effects, two corners, a calmer intensity, the season written out and a custom color. ```html ``` Every option is described on its own page: [intensity](/docs/options/intensity/), [color](/docs/options/color/), [size and opacity](/docs/options/size-and-opacity/) and the optional [badge](/docs/options/badge/). ## When you cannot edit the body tag Site builders and CMSs often hide the `` tag. This snippet loads the library and adds the classes from a script, so it works whether it is pasted in the head, in the footer or injected later by a tag manager. It adds to the existing body classes instead of replacing them. ```html ``` Step-by-step guides with the exact menu path for each builder are in [platforms](/platforms/). To build the classes for your own setup, use the [playground](/#playground). ## Turn effects on and off from code Because the library re-syncs whenever the body classes change, toggling a class is enough. This works in single-page apps and in any framework. ```js document.body.classList.toggle("halloween-eyes", someCondition); ``` Removing a class clears the matching effect from the screen immediately. It does not wait for the effect to finish fading out.