UnityScript versus JavaScript
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 ($) are not allowed in UnityScript identifiers as they are in JS identifiers.
<javascript>var lib$cosine = 3; // ERROR! in UnityScript</javascript>
