diff --git a/.gitignore b/.gitignore
index 4334b3d84..2e937c735 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,7 +15,6 @@
 /yosys
 /yosys.exe
 /yosys.js
-/yosys.html
 /yosys-abc
 /yosys-abc.exe
 /yosys-config
diff --git a/Makefile b/Makefile
index a7035008c..a301df2fc 100644
--- a/Makefile
+++ b/Makefile
@@ -113,12 +113,18 @@ LDLIBS =
 EXE = .js
 
 TARGETS := $(filter-out yosys-config,$(TARGETS))
-EXTRA_TARGETS += yosys.html viz.js
+EXTRA_TARGETS += yosysjs-$(YOSYS_VER).zip
 
 viz.js:
 	wget -O viz.js.part https://github.com/mdaines/viz.js/releases/download/0.0.3/viz.js
 	mv viz.js.part viz.js
 
+yosysjs-$(YOSYS_VER).zip: yosys.js viz.js misc/yosysjs/*
+	rm -rf yosysjs-$(YOSYS_VER) yosysjs-$(YOSYS_VER).zip
+	mkdir -p yosysjs-$(YOSYS_VER)
+	cp viz.js misc/yosysjs/* yosys.js yosysjs-$(YOSYS_VER)/
+	zip -r yosysjs-$(YOSYS_VER).zip yosysjs-$(YOSYS_VER)
+
 yosys.html: misc/yosys.html
 	$(P) cp misc/yosys.html yosys.html
 
diff --git a/kernel/driver.cc b/kernel/driver.cc
index 6df7cf2e8..69a7b8e15 100644
--- a/kernel/driver.cc
+++ b/kernel/driver.cc
@@ -93,7 +93,9 @@ void run(const char *command)
 
 const char *prompt()
 {
-	return create_prompt(yosys_get_design(), 0);
+	const char *p = create_prompt(yosys_get_design(), 0);
+	while (*p == '\n') p++;
+	return p;
 }
 
 #else /* EMSCRIPTEN */
diff --git a/misc/yosys.html b/misc/yosysjs/demo01.html
similarity index 98%
rename from misc/yosys.html
rename to misc/yosysjs/demo01.html
index 264a58f96..e0ba0248f 100644
--- a/misc/yosys.html
+++ b/misc/yosysjs/demo01.html
@@ -1,7 +1,7 @@
 <html><head>
-	<title>yosys.js example application</title>
+	<title>YosysJS Example Application #01</title>
 </head><body onload="document.getElementById('command').focus()">
-	<h1>yosys.js example application</h1>
+	<h1>YosysJS Example Application #01</h1>
 	<table width="100%"><tr><td><div id="tabs"></div></td><td align="right"><tt>[ <span onclick="load_example()">load example</span> ]</tt></td></tr></table>
 	<iframe id="viz" style="display: none"><script type="text/javascript" src="viz.js"></script></iframe>
 	<svg id="svg" style="display: none; position: absolute; padding: 10px; width: 100%; height: 80%;"></svg>
diff --git a/misc/yosysjs/demo02.html b/misc/yosysjs/demo02.html
new file mode 100644
index 000000000..ec33198c7
--- /dev/null
+++ b/misc/yosysjs/demo02.html
@@ -0,0 +1,102 @@
+<html><head>
+	<title>YosysJS Example Application #02</title>
+	<script type="text/javascript" src="yosysjs.js"></script>
+</head><body>
+	<div id="popup" style="position: fixed; left: 0; top: 0; width:100%; height:100%; text-align:center; z-index: 1000;"><div
+		style="width:300px; margin: 200px auto; background-color: #88f; border:3px dashed #000;
+		padding:15px; text-align:center;"><span id="popupmsg">Loading...</span></div>
+	</div>
+	<h1>YosysJS Example Application #02</h1>
+	<iframe id="ys" style="width: 800px; height: 100px;"></iframe><p/>
+	<textarea id="code" style="width: 800px; height: 300px;">
+// borrowed with some modifications from
+// http://www.ee.ed.ac.uk/~gerard/Teach/Verilog/manual/Example/lrgeEx2/cooley.html
+module up3down5(clock, data_in, up, down, carry_out, borrow_out, count_out, parity_out);
+
+input [8:0] data_in;
+input clock, up, down;
+
+output reg [8:0] count_out;
+output reg carry_out, borrow_out, parity_out;
+
+reg [9:0] cnt_up, cnt_dn;
+reg [8:0] count_nxt;
+
+always @(posedge clock)
+begin
+	cnt_dn = count_out - 3'b 101;
+	cnt_up = count_out + 2'b 11;
+
+	case ({up,down})
+		2'b 00 : count_nxt = data_in;
+		2'b 01 : count_nxt = cnt_dn;
+		2'b 10 : count_nxt = cnt_up;
+		2'b 11 : count_nxt = count_out;
+		default : count_nxt = 9'bX;
+	endcase
+
+	parity_out  &lt;= ^count_nxt;
+	carry_out   &lt;= up &amp; cnt_up[9];
+	borrow_out  &lt;= down &amp; cnt_dn[9];
+	count_out   &lt;= count_nxt;
+end
+
+endmodule
+	</textarea><p/>
+	<input type="button" value="Before Behavioral Synth" onclick="synth1()">
+	<input type="button" value="After Behavioral Synth" onclick="synth2()">
+	<input type="button" value="After RTL Synth" onclick="synth3()">
+	<input type="button" value="After Gate-Level Synth" onclick="synth4()"><p/>
+	<svg id="svg" width="800"></svg>
+	</td></tr></table>
+	<script type="text/javascript">
+		YosysJS.load_viz();
+		function on_ys_ready() {
+			document.getElementById('popup').style.visibility = 'hidden';
+			document.getElementById('popupmsg').textContent = 'Please wait..';
+		}
+		function synth1() {
+			function work() {
+				ys.write_file("input.v", document.getElementById('code').value);
+				ys.run('design -reset; read_verilog input.v; show -stretch');
+				YosysJS.dot_into_svg(ys.read_file('show.dot'), document.getElementById('svg'));
+				document.getElementById('popup').style.visibility = 'hidden';
+			}
+			document.getElementById('popup').style.visibility = 'visible';
+			window.setTimeout(work, 100);
+		}
+		function synth2() {
+			function work() {
+				ys.write_file("input.v", document.getElementById('code').value);
+				ys.run('design -reset; read_verilog input.v; proc; opt_clean; show -stretch');
+				YosysJS.dot_into_svg(ys.read_file('show.dot'), document.getElementById('svg'));
+				document.getElementById('popup').style.visibility = 'hidden';
+			}
+			document.getElementById('popup').style.visibility = 'visible';
+			window.setTimeout(work, 100);
+		}
+		function synth3() {
+			function work() {
+				ys.write_file("input.v", document.getElementById('code').value);
+				ys.run('design -reset; read_verilog input.v; synth -run coarse; show -stretch');
+				YosysJS.dot_into_svg(ys.read_file('show.dot'), document.getElementById('svg'));
+				document.getElementById('popup').style.visibility = 'hidden';
+			}
+			document.getElementById('popup').style.visibility = 'visible';
+			window.setTimeout(work, 100);
+		}
+		function synth4() {
+			function work() {
+				ys.write_file("input.v", document.getElementById('code').value);
+				ys.run('design -reset; read_verilog input.v; synth -run coarse; synth -run fine; show -stretch');
+				YosysJS.dot_into_svg(ys.read_file('show.dot'), document.getElementById('svg'));
+				document.getElementById('popup').style.visibility = 'hidden';
+			}
+			document.getElementById('popup').style.visibility = 'visible';
+			window.setTimeout(work, 100);
+		}
+		var ys = YosysJS.create('ys', on_ys_ready);
+		ys.verbose = true;
+		ys.echo = true;
+	</script>
+</body></html>
diff --git a/misc/yosysjs/yosysjs.js b/misc/yosysjs/yosysjs.js
new file mode 100644
index 000000000..ad6df348b
--- /dev/null
+++ b/misc/yosysjs/yosysjs.js
@@ -0,0 +1,159 @@
+var YosysJS = new function() {
+	this.script_element = document.currentScript;
+	this.viz_element = undefined;
+
+	this.url_prefix = this.script_element.src.replace(/[^/]+$/, '')
+
+	this.load_viz = function() {
+		if (this.viz_element)
+			return;
+
+		this.viz_element = document.createElement('iframe')
+		this.viz_element.style.display = 'none'
+		document.body.appendChild(this.viz_element);
+
+		this.viz_element.contentWindow.document.open()
+		this.viz_element.contentWindow.document.write('<script type="text/javascript" src="' + this.url_prefix + 'viz.js"></' + 'script>');
+		this.viz_element.contentWindow.document.close()
+	}
+
+	this.dot_to_svg = function(dot_text) {
+		return this.viz_element.contentWindow.Viz(dot_text, "svg");
+	}
+
+	this.dot_into_svg = function(dot_text, svg_element) {
+		svg_element.innerHTML = this.dot_to_svg(dot_text);
+		c = svg_element.firstChild;
+		while (c) {
+			if (c.tagName == 'svg') {
+				while (c.firstChild)
+					svg_element.appendChild(c.firstChild);
+				svg_element.setAttribute('viewBox', c.getAttribute('viewBox'));
+				// svg_element.removeChild(c);
+				break;
+			}
+			c = c.nextSibling;
+		}
+	}
+
+	this.create = function(reference_element, on_ready) {
+		var ys = new Object();
+		ys.init_script = "";
+		ys.ready = false;
+		ys.verbose = false;
+		ys.echo = false;
+
+		if (typeof(reference_element) == 'string')
+			reference_element = document.getElementById(reference_element);
+
+		if (reference_element) {
+			if (reference_element.tagName == 'textarea')
+				ys.init_script = reference_element.value;
+		
+			if (reference_element.tagName == 'iframe') {
+				ys.iframe_element = reference_element;
+			} else {
+				ys.iframe_element = document.createElement('iframe');
+				ys.iframe_element.id = reference_element.id;
+				for (i in reference_element.style)
+					ys.iframe_element.style[i] = reference_element.style[i];
+				reference_element.parentNode.insertBefore(ys.iframe_element, reference_element);
+				reference_element.parentNode.removeChild(reference_element);
+			}
+		} else {
+			ys.iframe_element = document.createElement('iframe');
+			document.body.appendChild(ys.iframe_element);
+		}
+
+		var return_buffer = "";
+		var last_line_empty = false;
+
+		var win = ys.iframe_element.contentWindow;
+		var doc = ys.iframe_element.contentWindow.document;
+		var mod = ys.iframe_element.contentWindow.Module = {
+			print: function(text) {
+				return_buffer += text + "\n";
+				if (ys.verbose) {
+					last_line_empty = text == "";
+					span = doc.createElement('span');
+					span.textContent = text + "\n";
+					span.style.fontFamily = 'monospace';
+					span.style.whiteSpace = 'pre';
+					doc.body.appendChild(span);
+					win.scrollTo(0, doc.body.scrollHeight)
+				}
+				ys.ready = true;
+			},
+			printErr: function(text) {
+				return_buffer += text + "\n";
+				last_line_empty = text == "";
+				span = doc.createElement('span');
+				span.textContent = text + "\n";
+				span.style.fontFamily = 'monospace';
+				span.style.whiteSpace = 'pre';
+				span.style.color = 'red';
+				doc.body.appendChild(span);
+				win.scrollTo(0, doc.body.scrollHeight)
+			},
+		};
+
+		ys.write = function(text) {
+			last_line_empty = text == "";
+			span = doc.createElement('span');
+			span.textContent = text + "\n";
+			span.style.fontFamily = 'monospace';
+			span.style.whiteSpace = 'pre';
+			doc.body.appendChild(span);
+			win.scrollTo(0, doc.body.scrollHeight)
+		}
+
+		ys.prompt = function() {
+			return mod.ccall('prompt', 'string', [], [])
+		}
+
+		ys.run = function(cmd) {
+			return_buffer = "";
+			if (ys.echo) {
+				if (!last_line_empty)
+					ys.write("");
+				ys.write(ys.prompt() + cmd);
+			}
+			mod.ccall('run', '', ['string'], [cmd]);
+			return return_buffer;
+		}
+
+		ys.read_file = function(filename) {
+			return win.FS.readFile(filename, {encoding: 'utf8'});
+		}
+
+		ys.write_file = function(filename, text) {
+			return win.FS.writeFile(filename, text, {encoding: 'utf8'});
+		}
+
+		ys.read_dir = function(dirname) {
+			return win.FS.readdir(dirname);
+		}
+
+		el = doc.createElement('script');
+		el.type = 'text/javascript';
+		el.src = this.url_prefix + 'yosys.js';
+		doc.head.appendChild(el);
+
+		if (on_ready || ys.init_script) {
+			function check_ready() {
+				if (ys.ready) {
+					if (ys.init_script) {
+						ys.write_file("/script.ys", ys.init_script);
+						ys.run("script /script.ys");
+					}
+					if (on_ready)
+						on_ready(ys);
+				} else
+					window.setTimeout(check_ready, 100);
+			}
+			window.setTimeout(check_ready, 100);
+		}
+
+		return ys;
+	}
+}
