A Boot task for generating bookmarklets from ClojureScript namespaces
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Clojars Project

A Boot task for generating bookmarklets from ClojureScript namespaces, allowing you to write bookmarklets in ClojureScript! 📖 🔖


Add adzerk/boot-bookmarklet to your build.boot dependencies and require/refer in the task:

(set-env! :dependencies '[[adzerk/boot-bookmarklet "X.Y.Z" :scope "test"]])
(require '[adzerk.boot-bookmarklet :refer (bookmarklet external-bookmarklet)])


  • bookmarklet compiles your ClojureScript into JavaScript and stuffs the code for each namespace into a javascript:<CODE HERE> bookmarklet link.

    bookmarklet is convenient if your bookmarklet happens to be small enough that the compiled, URL-encoded JavaScript can fit in the bookmarklet link. The character limit for a bookmarklet link varies from browser to browser.

  • external-bookmarklet takes any number of URLs to hosted .js files and generates a bookmarklet link for each file that sources and runs it.

    Once your code reaches a certain size, you will hit the character limit and your bookmarklet won't work anymore. To get around this, you can host your compiled .js file somewhere (e.g. Dropbox, S3) and use external-bookmarklet to generate a small bookmarklet that simply loads the hosted .js file.


The bookmarklet task takes an (optional) option :ids which is a set of strings identifying cljs files on the source path:

(deftask build
    (bookmarklet :ids #{"lobster"})

This will match a file lobster.cljs if it exists in the source paths.

When run, this task will compile the namespace of each ClojureScript file into a standalone JavaScript file (compiled with advanced optimizations), read the contents of the file, and generate an HTML file called bookmarklets.html, containing a bookmarklet link for each ClojureScript file identified in :ids.

You can then open target/bookmarklets.html in your browser and drag the bookmarklet link into your bookmarks.

(deftask build

If no :ids argument is provided, the bookmarklets task will generate a bookmarklet for every ClojureScript file found in the source paths. This may be more convenient if you want to create a project that is just a collection of bookmarklets, and you want bookmarklets to generate a single HTML page containing a bookmarklet link for each ClojureScript namespace.

You can, of course, also run the bookmarklet task from the command-line:

boot bookmarklet -i foo -i bar target


In order to use external-bookmarklet, your bookmarklet code must already be compiled to JavaScript and hosted somewhere. Once you have the URL to your hosted .js file, you can provide it to external-bookmarklet via the -u/--urls option, and it will generate a bookmarklets.html file containing a bookmarklet link which, when clicked, will fetch and run your hosted .js file in the context of the current page.

boot external-bookmarklet -u http://path.to/my/hosted.js
(deftask link
  (external-bookmarklet :urls #{"http://path.to/my/hosted.js"}))

If you provide multiple URLs, the generated HTML file will contain one bookmarklet link per .js file.

TODO: example build task that watches for changes, updates the hosted.js, and generates bookmarklets.html with an external bookmarklet


The simplest of ClojureScript bookmarklets might look something like this:

(ns example.bookmarklet)

(js/alert "o hai!")

A more complex example project is in the works. Stay tuned!


There are probably all kinds of ways boot-bookmarklet could be improved. Pull Requests welcome!


Copyright © 2016 Adzerk

Distributed under the Eclipse Public License version 1.0.