javascript in examples (scopes, closures, this)

I am sure you know Javascript. Or maybe you don't. Or maybe you want to play with it - then download Rhino from Mozilla - it is an interactive Javascript interpreter (to run it, do this: java -jar js.jar. Rhino's version of Javascript has print(message) and load(filename) functions, but does not have alert(message) - so below I will use print() insteead of the usual alert()

var obj = new Object()
obj.myname = "John Walker"

var my = "my"
var name = "name"
print(obj[my + name])

This code will duly print "John Walker".

How about this:( Read more... )

var x = new Object()
x.a = 2
var y = new Object()
y.a = "The A of Y"

y.f = function(param) { 
  var self = this
  param.f = function(arg) { print(self.a + arg + this.a) }
}

y.f(x)
x.f(" is not ")

And the answer is... "The A of Y is not 2"