marker.js 3 is a JavaScript image annotation library and suite of web components for your web applications. marker.js enables your users to add visual commentary, highlight, or tag information on images. This all can be done with just a few lines of code. The resulting markups can be saved for future use, modified as needed, displayed as interactive overlays, or rendered into static graphics.
marker.js suite consists of three core parts:
marker.js 3 is a suite of "headless" web components for image annotation and markup. The core marker.js 3 library provides the tools to enable interactive drawing and editing of various markers but doesn't include any toolbars, property panels, or other UI elements. This way you get the best of both worlds — advanced annotation features and complete adaptability to your app's UI style and design system.
A separate marker.js UI package containing a pre-made editor and viewer UIs is now available. It's a great way to get a complete annotation editor in just a few lines of code.
npm install @markerjs/markerjs3
The library includes TypeScript type definitions out of the box.
Import MarkerArea from @markerjs/markerjs3:
import { MarkerArea } from "@markerjs/markerjs3";
In the code below we assume that you have an HTMLImageElement as targetImage. It can be a reference to an image you already have on the page or you can simply create it with something like this:
const targetImg = document.createElement("img");
targetImg.src = "./sample.jpg";
Now you just need to create an instance of MarkerArea, set its targetImage property and add it to the page:
const markerArea = new MarkerArea();
markerArea.targetImage = targetImg;
editorContainerDiv.appendChild(markerArea);
To initiate creation of a marker you just call createMarker() and pass it the name (or type) of the marker you want to create. So, if you have a button with id addFrameButton you can make it create a new FrameMarker with something like this:
document.querySelector("#addButton")?.addEventListener("click", () => {
markerArea.createMarker("FrameMarker");
});
And whenever you want to save state (current annotation) you just call getState():
document.querySelector("#saveStateButton")?.addEventListener("click", () => {
const state = markerArea.getState();
console.log(state);
});
To render the annotation as a static image you use Renderer.
import { MarkerArea, Renderer } from "@markerjs/markerjs3";
Just create an instance of it and pass the annotation state to the rasterize() method:
const renderer = new Renderer();
renderer.targetImage = targetImg;
const dataUrl = await renderer.rasterize(markerArea.getState());
const img = document.createElement("img");
img.src = dataUrl;
someDiv.appendChild(img);
Note that the rasterize() method is asynchronous and requires using async/await or Promise handling.
To show dynamic annotation overlays on top of the original image you use MarkerView.
import { MarkerView } from "@markerjs/markerjs3";
const markerView = new MarkerView();
markerView.targetImage = targetImg;
viewerContainer.appendChild(markerView);
markerView.show(savedState);
Check out the "work-in-progress" demo here. It covers most of the available features with no extra bells or whistles. While it's made with React it is purposefully light on React-specific stuff and "best practices" to just focus on marker.js 3 related things.