--- layout: api title: "v2.1.2 JavaScript Library: Global Switches" categories: api version: v2.1.2 permalink: /api/v2.1.2/l-global ---

## Global Switches

Global switches are created for rare cases and generally make Leaflet to not detect a particular browser feature even if it's there. You need to set the switch as a global variable to `true` before including Leaflet on the page, like this:

    <script>L_PREFER_CANVAS = true;</script>
    <script src="leaflet.js"></script>

Switch | Description
--- | ---
`L_PREFER_CANVAS` | Forces Leaflet to use the Canvas back-end (if available) for vector layers instead of SVG. This can increase performance considerably in some cases (e.g. many thousands of circle markers on the map).
`L_NO_TOUCH` | Forces Leaflet to not use touch events even if it detects them.
`L_DISABLE_3D` | Forces Leaflet to not use hardware-accelerated CSS 3D transforms for positioning (which may cause glitches in some rare environments) even if they're supported.