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Portable JS Gnuplot

This is the result of compiling gnuplot with emscripten, combined with an API so it is usable straight out of the box in your browser. 
The www directory contains the necessary files and a compiled version of gnuplot 4.6.3. The gnuplot-4.6.3 directory contains everything to 
build the gnuplot sources with emscripten. 

How to compile gnuplot

- Install llvm / emscripten, follow instructions at
- Download the gnuplot-4.6.3.tar.gz sources at and untar.
- Copy the contents of this repo's gnuplot-4.6.3 into the folder where you unpacked the sources (should be the same name).
- [optional] adjust src/term.h and remove unneeded terminals to reduce final size
- [optional] patch src/axis.c with the patch file to fix axis descriptions: cd src;patch <../gnuplot-4.6.3.patch 
- Run em_make to configure and build, you should have a gnuplot.js in your directory. WAIT at the end! The final step takes long. 

How the API works

The gnuplot API (gnuplot_api.js) creates a worker (JS-thread) that loads gnuplot.js and handles all the work. No browser checks are done to check for HTML5 features. 
The API lets you interact with the worker to "upload" or "download" files. Emscripten uses a mock-up for file I/O, so keep in mind that files are kept in memory as arrays
and that you need to push / pull any file-content to / from the fake file system within the worker. The API provides some convenience functions for this.

The demo site from the www directory is online at

A minimal implementation should look like this (untested! see index.html for working version):

<img id="result"/>
<script src='gnuplot_api.js'></script>
    gnuplot = new Gnuplot('gnuplot.js');
    //gnuplot.putFile("myData.dat", "1 2 3 4 5 6 7 8 9 0"); // No callback needed here"my gnuplot script as a string", function(e) {
	gnuplot.getFile('out.svg', function(e) {
	    if (!e.content) {
               alert("Output file out.svg not found!");
           var img = document.getElementById('result');
           try {
				var ab = new Uint8Array(e.content);
				var blob = new Blob([ab], {"type": "image\/svg+xml"});
				window.URL = window.URL || window.webkitURL;
				img.src = window.URL.createObjectURL(blob);
           } catch (err) { // in case blob / URL missing, fallback to data-uri
                var rstr = '';
	            for (var i = 0; i < e.content.length; i++)
	              rstr += String.fromCharCode(e.content[i]);
	            img.src = 'data:image\/svg+xml;base64,' + btoa(rstr);


An API to a JavaScript gnuplot port using emscripten.







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