UnityScript versus JavaScript

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(JavaScript is class-free)
Line 6: Line 6:
 
}
 
}
 
var c = new Machine(2);
 
var c = new Machine(2);
print(typeof c.announce); // undefined
+
print(typeof c.announce); // "undefined"
  
 
Machine.prototype.announce = function() {
 
Machine.prototype.announce = function() {
 
   print("I am a "+this.kind+".");
 
   print("I am a "+this.kind+".");
 
};
 
};
print(typeof c.announce); // function
+
 
 +
print(typeof c.announce); // "function"
 
c.announce();</javascript>
 
c.announce();</javascript>
  

Revision as of 17:56, 7 April 2011

JavaScript is class-free

JavaScript has no classes. This is because it's a prototypal language, and not a classical one. Inheritance happens with [more dynamic] objects, rather than [unchanging] classes. <javascript>function Machine(x) {

  this.kind = ["bulldozer", "lathe", "car"][x];

} var c = new Machine(2); print(typeof c.announce); // "undefined"

Machine.prototype.announce = function() {

  print("I am a "+this.kind+".");

};

print(typeof c.announce); // "function" c.announce();</javascript>

Dynamic typing is inefficient

This code is valid in both UnityScript and JavaScript: <javascript>var x; x = 3;</javascript> However, it is inefficient in UnityScript because it causes x to be dynamically typed. For faster runtime execution, use one of the two static typing syntaxes. <javascript>var x = 3; // type `int` is inferred, typed statically</javascript>

<javascript>var x : int; // typed statically x = 3;</javascript>

Privacy

In JavaScript, privacy is rather unconventional.

<javascript>function Person() {

  var secret = "I am a mass murderer."; // private
  this.speak = function() { print("Don't make me tell you my secret! "+secret); }; // prints secret

} var bob = new Person(); print(bob.secret); // undefined</javascript>

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