## page was renamed from SpiderMonkey
= SpiderMonkey =
SpiderMonkey is Mozilla's [[Javascript]] engine written in C/C++. It is used in various Mozilla products, including Firefox, and is available under the MPL2.

== Example code ==
{{{#!highlight javascript
#!/usr/bin/js
function CTest(){
  this.counter=0;
}


CTest.prototype.increment=function(){
  this.counter++;
};

CTest.prototype.show=function(){
  putstr(this.counter);
  putstr("\r\n");
};

var c = new CTest();
var d = new CTest();
c.increment();
c.increment();
c.increment();
c.show();

d.increment();
d.increment();
d.show();
}}}

Run it with:
 * chmod 755 test.js
 * ./test.js

SpiderMonkey is installed on Slackware 14.

== Windows binary ==
 * https://archive.mozilla.org/pub/firefox/nightly/latest-mozilla-central/jsshell-win64.zip

== Example of prototype/inheritance ==
 * https://developer.mozilla.org/en/docs/Web/JavaScript/Inheritance_and_the_prototype_chain
When it comes to inheritance, Javascript only has one construct: objects. Each object has an internal link to another object called its prototype (__proto__).

Javascript objects are dynamic "bags" of properties (referred to as own properties). JavaScript objects have a link to a prototype object.

{{{#!highlight javascript
// https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects
var a = {"key":"A value"};
var b = {};
b.__proto__ = a; // set a as prototype of b . b inherits a 
/*var b = Object.create( a );*/
b.other="aaaa";
if( ! b.hasOwnProperty('key') ) print( "b doesn't have own property key" );
if( b.hasOwnProperty('other') ) print( b.other );

if( a.hasOwnProperty('key') ) print( a['key'] );
if( a.hasOwnProperty('other') ) print( a['other'] );

b.key='Other Value'; // b has own key "key" and a has also key "key" with different value

print('\nkeys in object a');
for(var key in a){
    print( key ,'->' , a[key] );
}

print('\nKeys in object b');
for(var key in b){
  print( key ,'->' , b[key] );
}

print('Value for key in prototype of b' , b.__proto__.key );

//-------
print();
function f(){
  this.propx='asdf';
  this.fn=function(){print("aaaa");};
  this.nr=123.4;
}

f.prototype.protoFn=function(){ print("bbb"); };

var x = new f();
print('x instance of f '  , x instanceof f);
print('x is type of ' + typeof f);
print('x instance of object '  , x instanceof Object);
print('x instance of Array '  , x instanceof Array);

for(var key in x){
  print( key ,':' , x[key] , x.hasOwnProperty(key) , typeof x[key]  );
}

print( JSON.stringify( x ) );
}}}