UnityScript versus JavaScript

From Unify Community Wiki
(Difference between revisions)
Jump to: navigation, search
(Privacy)
(No Bling)
Line 61: Line 61:
 
== No Bling ==  
 
== No Bling ==  
  
Dollar signs ($) are not allowed in UnityScript identifiers as they are in JS identifiers.
+
Dollar signs ($) are not allowed in UnityScript identifiers as they are in JS identifiers. (In JS, the symbol is often used for c-style namespacing or as the name of a do-everything function.)
  
 
<javascript>var lib$cosine = 3; // ERROR! in UnityScript</javascript>
 
<javascript>var lib$cosine = 3; // ERROR! in UnityScript</javascript>

Revision as of 17:34, 10 April 2011

Contents

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>

UnityScript has classes, and functions cannot create objects as in JavaScript. <javascript> class

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() { // (this is the *JavaScript* way of doing privacy)

  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 bob.speak(); // prints "Don't make me tell you my secret! I am a mass murderer."</javascript>

In UnityScript, it can be more intuitive.

<javascript>class Person { // UnityScript only; impossible in JavaScript

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

}

var bob = new Person(); print(bob.secret); // undefined bob.speak(); // prints "Don't make me tell you my secret! I am a mass murderer."</javascript>

No Bling

Dollar signs ($) are not allowed in UnityScript identifiers as they are in JS identifiers. (In JS, the symbol is often used for c-style namespacing or as the name of a do-everything function.)

<javascript>var lib$cosine = 3; // ERROR! in UnityScript</javascript>

Personal tools
Namespaces

Variants
Actions
Navigation
Extras
Toolbox