<!DOCTYPE html><html><head><link href="style.css" rel="stylesheet"><title>MuJS Examples</title></head> <body> <header><h1>MuJS Examples</h1></header> <nav><a href="introduction.html">Introduction</a><a href="reference.html">Reference</a><a href="examples.html">Examples</a><a href="license.html">License</a><a href="http://git.ghostscript.com/?p=mujs.git;a=summary">Source</a><a href="https://bugs.ghostscript.com/">Bugs</a></nav> <article> <h2>A stand-alone interpreter</h2> <pre>#include &lt;stdio.h&gt;#include &lt;mujs.h&gt; int main(int argc, char **argv){	char line[256];	js_State *J = js_newstate(NULL, NULL, JS_STRICT);	while (fgets(line, sizeof line, stdin))		js_dostring(J, line);	js_freestate(J);}</pre> <h2>Hello, world!</h2> <pre>#include &lt;stdio.h&gt;#include &lt;mujs.h&gt; static void hello(js_State *J){	const char *name = js_tostring(J, 1);	printf("Hello, %s!\n", name);	js_pushundefined(J);} int main(int argc, char **argv){	js_State *J = js_newstate(NULL, NULL, JS_STRICT); 	js_newcfunction(J, hello, "hello", 1);	js_setglobal(J, "hello"); 	js_dostring(J, "hello('world');"); 	js_freestate(J);}</pre> <h2>Configuration file</h2> <pre>js_dofile(J, "config.js") js_getglobal(J, "foo");foo = js_tonumber(J, -1);js_pop(J, 1);</pre> <h2>Object manipulation</h2> <pre>// t = { foo: 42, bar: true } js_newobject(J);{	js_pushnumber(J, 42);	js_setproperty(J, -2, "foo");	js_pushboolean(J, 1);	js_setproperty(J, -2, "bar");}js_setglobal(J, "t");</pre> <h2>Callbacks from C to JS (by name)</h2> <pre>static int call_callback(js_State *J, const char *arg1, int arg2){	int result; 	/* Find the function to call. */	js_getglobal(J, "my_callback"); 	/* Push arguments to function. */	js_pushnull(J); /* the 'this' object to use */	js_pushstring(J, arg1);	js_pushnumber(J, arg2); 	/* Call function and check for exceptions. */	if (js_pcall(J, 2)) {		fprintf(stderr, "an exception occurred in the javascript callback\n");		js_pop(J, 1);		return -1;	} 	/* Retrieve return value. */	result = js_tonumber(J, -1);	js_pop(J, 1); 	return result;}</pre> <h2>Callbacks from C to JS</h2> <pre>const char *handle = NULL; /* handle to stowed away js function */ static void set_callback(js_State *J){	if (handle)		js_unref(J, handle); /* delete old function */	js_copy(J, 1);	handle = js_ref(J); /* stow the js function in the registry */} static void call_callback(js_State *J, int arg1, int arg2){	js_getregistry(J, handle); /* retrieve the js function from the registry */	js_pushnull(J);	js_pushnumber(J, arg1);	js_pushnumber(J, arg2);	js_pcall(J, 2);	js_pop(J, 1);}</pre> <h2>Complete userdata example</h2> <pre>#include &lt;stdio.h&gt;#include &lt;mujs.h&gt; #define TAG "File" static void new_File(js_State *J){	FILE *file; 	if (js_isundefined(J, 1)) {		file = stdin;	} else {		const char *filename = js_tostring(J, 1);		file = fopen(filename, "r");		if (!file)			js_error(J, "cannot open file: '%s'", filename);	} 	js_currentfunction(J);	js_getproperty(J, -1, "prototype");	js_newuserdata(J, TAG, file);} static void File_prototype_readByte(js_State *J){	FILE *file = js_touserdata(J, 0, TAG);	js_pushnumber(J, getc(file));} static void File_prototype_readLine(js_State *J){	char line[256], *s;	FILE *file = js_touserdata(J, 0, TAG);	s = fgets(line, sizeof line, file);	if (s)		js_pushstring(J, line);	else		js_pushnull(J);} static void File_prototype_close(js_State *J){	FILE *file = js_touserdata(J, 0, TAG);	fclose(file);	js_pushundefined(J);} void initfile(js_State *J){	js_getglobal(J, "Object");	js_getproperty(J, -1, "prototype");	// File.prototype.[[Prototype]] = Object.prototype	js_newuserdata(J, TAG, stdin);		// File.prototype.[[Userdata]] = stdin	{		js_newcfunction(J, File_prototype_readByte, "File.prototype.readByte", 0);		js_defproperty(J, -2, "readByte", JS_DONTENUM); 		js_newcfunction(J, File_prototype_readLine, "File.prototype.readLine", 0);		js_defproperty(J, -2, "readLine", JS_DONTENUM); 		js_newcfunction(J, File_prototype_close, "File.prototype.close", 0);		js_defproperty(J, -2, "close", JS_DONTENUM);	}	js_newcconstructor(J, new_File, new_File, "File", 1);	js_defglobal(J, "File", JS_DONTENUM);}</pre> </article> <footer><a href="http://artifex.com"><img src="artifex-logo.png" align="right"></a>Copyright &copy; 2013-2017 Artifex Software Inc.</footer> </body></html>