TrendChart Elements

Web components to generate simple, light and responsive charts representing trends.

It is often useful to display some simple charts to represent a data visualization trend without the need of a big chart library, TrendChart Elements is made for that. The aim was to be as plug-and-play as possible, like native HTML tags, so all the configuration is made with CSS variables and HTML attributes. It's fully responsive with built-in basic tooltip.

10.5ko minified and gzipped, tree-shakeable, written in TypeScript, and no dependency except Lit to create web components (50% of the package size). Tested on modern browsers : Chrome >= 73, Firefox >= 63, Edge >= 79, Safari >= 12.

Installation

Install the package with NPM :

npm install @weblogin/trendchart-elements

Import into your project code :

// All the charts
import '@weblogin/trendchart-elements';
// Only some charts
import { TcLine } from "@weblogin/trendchart-elements";

Update from V1

Some of the markup has changed to make room for new features, have a look at the documentation below to find the new names.

Usage

Check out the demo page for various charts stylings and use cases.

<tc-line values="[12,10,12,11,7,6,8,10,12]"></tc-line>
<tc-pie values="[35,68,22,16]"></tc-pie>
<tc-bar values="[11,7,6,8,10,12,8,10,12]"></tc-bar>
<tc-stack values="[24,18,19,7]"></tc-stack>

Use CSS to change the width and height of the chart, because they are responsive you can use percentages.

In some cases you'll need to have a radius around the chart if its container has one, for that just add a border-radius CSS rule to the chart.

Charts configuration is made with CSS variables and HTML attributes :

HTML Attributes

Name	Default	Description
➡️ All charts
values	-	Required - Array of numbers for the values, at least 2 for line and bar charts. Example : values="[12,10,11]"
labels	[]	Optional - Array of strings for the labels corresponding to the values, it needs to be the same length as values array. Example : labels='["A","B","C"]'
static	false	Optional - Boolean to disable tooltip and hover styling
tooltip-disabled	false	Optional - Boolean to disable tooltip
tooltip-format	@L @V	Optional - String to format the tooltip text. Two placeholders are available, @V for the current value and @L for the current label if present
max	0	Optional - Number to change the max scale of the chart
➡️ Line chart
min	0	Optional - Number to change the min scale of the chart
weight	2	Optional - Number for the line weight
point	undefined	Optional - Number for the point weight, if not set it will be weight + 6
inside	false	Optional - Boolean to draw the points inside the chart. Because the line touch the edges by default, the points have half of their size outside the chart. Usefull if all points are visible
➡️ Bar chart
min	0	Optional - Number to change the min scale of the chart
radius	2	Optional - Number for the radius of the bars
horizontal	false	Optional - Boolean to change the orientation to horizontal
gap	2	Optional - Number for the gap between bars
➡️ Stack chart
radius	2	Optional - Number for the radius of the global bar
horizontal	false	Optional - Boolean to change the orientation to horizontal
gap	2	Optional - Number for the gap between bars
➡️ Pie chart
donut	undefined	Optional - Number to create a donut of the given weight
rotate	0	Optional - Number in degrees to rotate the chart, 0 being the top
gap	2	Optional - Number for the gap between slices

For boolean ones you just have to set them on the tag, like this :

<tc-bar values="[3,9,10]" static><tc-bar>

CSS Variables

Name	Default	Description
➡️ All charts
--shape-color	#597BFC	-
--shape-opacity	1	-
--residual-color	black	The residual represent unused space, for example if you set a max of 100 but the highest value is lower
--residual-opacity	0	-
--tooltip-font-color	white	-
--tooltip-font-size	0.875em	-
--tooltip-font-weight	bold	-
--tooltip-radius	3px	-
--tooltip-padding	3px 4px	-
--tooltip-background	black	-
--tooltip-shadow	none	-
➡️ Line chart
--area-color	--shape-color	The area represent the space under the line
--area-opacity	0	-
--point-inner-color	--shape-color	-
--point-border-color	--shape-color	-
--point-opacity	0	-
--point-opacity-active	1	-
➡️ Bar / Stack / Pie chart
--shape-color-x	--shape-color	Color of the x shape starting at 1 : --shape-color-1, --shape-color-2, etc
--shape-opacity-active	0.5	Opacity of the current active shape

Events

Several custom events are fired so you can react to them. The detail property on the event contains associated data like the index and value.

Name	Description
shape-enter	Fire on mouse enter a value shape
shape-leave	Fire on mouse leave a value shape
shape-click	Fire on mouse click on a value shape

JS API

Even if TrendChart Elements is supposed to be used as a simple chart system, several properties are exposed so you can interact with the chart programmatically. In addition to the HTML Attributes above, here are some other usefull ones :

Name	Description
valueShapes	Array of valueShape objects. Each represent a value that will be displayed in the chart
valueShapeActive	Getter for the current active valueShape object
active	Index of the current active valueShape, can be used to manually set the active index

// <tc-line values="[12,10,12,11,7,6,8,10,12]"></tc-line>
const lineChart = document.querySelector('tc-line');
lineChart.active = 3;

License

TrendChart Elements is licensed under the MIT license.