Overview
At its core, Svelte Flow is about creating interactive flowgraphs - a collection of nodes connected by edges. While this might sound simple in theory, Svelte Flow provides the foundation for building complex interactive diagrams:
- An infinite, interactive canvas for your flowgraph
- The ability to render and connect nodes with edges
- Everything is built using standard Svelte components
To help you understand the terminology we use throughout the documentation, take a look at the example flow below.
Nodes
Svelte Flow has a few default node types out of the box, but customization is where the magic of Svelte Flow truly happens. You can design your nodes to work exactly the way you need them to—whether that’s embedding interactive form elements, displaying dynamic data visualizations, or even incorporating multiple connection handles. Svelte Flow lays the foundation, and your imagination does the rest.
We have a guide on creating your own Custom Nodes and you can find all the options for customizing your nodes in the Node reference.
Handles
A handle (also known as a “port” in other libraries) is the attachment point where an edge
connects to a node. By default, they appear as grey circles on the top, bottom, left, or
right sides of a node. But they are just div elements, and can be positioned and styled
any way you’d like. When creating a custom node, you can include as many handles as
needed. For more information, refer to the Handle page.
Edges
Edges connect nodes. Every edge needs a target and a source node. Svelte Flow comes with
four built-in edge types: default (bezier), smoothstep,
step, and straight. An edge is an SVG path that can be styled with CSS and is
completely customizable. If you are using multiple handles, you can reference them
individually to create multiple connections for a node.
Like custom nodes, you can also customize edges. Things that people do with custom edges include:
- Adding buttons to remove edges
- Custom routing behavior
- Complex styling or interactions that cannot be solved with just one SVG path
For more information, refer to the Edges page.
Selection
You can select an edge or a node by clicking on it. If you want to select multiple
nodes/edges via clicking, you can hold the Meta/Control key and click on multiple
elements to select them. If you want to change the keyboard key for multiselection to
something else, you can use the
multiSelectionKey prop.
You can also select multiple edges/nodes by holding down Shift and dragging the mouse to
make a selection box. When you release the mouse, any node or edge that falls within the
selection box is selected. If you want to change the keyboard key for this behavior, you
can use the selectionKey prop.
Selected nodes and edges are elevated (assigned a higher zIndex than other elements), so
that they are shown on top of all the other elements.
For default edges and nodes, selection is shown by a darker stroke/border than usual. If
you are using a custom node/edge, you can use the selected prop to customize selection
appearance inside your custom component.
Connection line
Svelte Flow has built-in functionality that allows you to click and drag from one handle to another to create a new edge. While dragging, the placeholder edge is referred to as a connection line. The connection line comes with the same four built-in types as edges and is customizable. You can find the props for configuring the connection line in the connection props reference.
Viewport
All of Svelte Flow is contained within the viewport. Each node has an x- and y-coordinate, which indicates its position within the viewport. The viewport has x, y, and zoom values. When you drag the pane, you change the x and y coordinates. When you zoom in or out, you alter the zoom level. You can read more about the viewport in the Viewport page.