mcanthony/segment

A little JavaScript class (without dependencies) to draw and animate SVG path strokes

Segment

A little JavaScript class (without dependencies) to draw and animate SVG path strokes.

See the DEMO.

Read this article to understand how it works.

Basic usage

HTML

Add the segment script, and define a path somewhere.

<script src="/dist/segment.min.js"></script>

<svg>
  <path id="my-path" ...>
</svg>

JavaScript

Initialize a new Segment with the path. Then draw a segment of stroke every time you want with: .draw(begin, end, duration, options).

var myPath = document.getElementById("my-path"),
    segment = new Segment(myPath);

segment.draw("25%", "75% - 10", 1);

Constructor

The Segment constructor asks for 3 parameters:

• path: DOM element to draw.
• begin (optional, default 0): Length to start drawing the stroke.
• end (optional, default 100%): Length to finish drawing the stroke.

Method draw(begin, end, duration, options)

Name	Type	Default	Description
begin	string	0	Path length to start drawing.
end	string	100%	Path length to finish drawing.
duration	float	0	Duration (in seconds) of the animation.
options	object	null	Options for animation in object notation.

Note that begin and end can be negative values and can be written in any of these ways:

• floatValue
• percent
• percent + floatValue
• percent - floatValue

All possible options for draw method

Name	Type	Default	Description
delay	float	0	Waiting time (in seconds) to start drawing.
easing	function	linear	Easing function (normalized). I highly recommend d3-ease.
circular	boolean	false	If true, when the stroke reaches the end of the path it will resume at the beginning. The same applies in the opposite direction.
callback	function	null	Function to call when the animation is done.

Example

function cubicIn(t) {
    return t * t * t;
}

function done() {
    alert("Done!");
}

segment.draw("-25%", "75% - 10", 1, {delay: 0.5, easing: cubicIn, circular: true, callback: done});

Animating with another library

It's possible to animate the path stroke using another JavaScript library, like GSAP. Segments offers a method called strokeDasharray that is useful for this issue. Here is an example using TweenLite (with CSSPlugin).

TweenLite.to(path, 1, { strokeDasharray: segment.strokeDasharray(begin, end) });