es5.js

"use strict"; // strict mode doesn't work, but it WOULD need to come in at the top of the file

// http://www.slideshare.net/kangax/say-hello-to-ecmascript-5
// http://davidflanagan.com/Talks/es5/slides.html
// http://www.slideshare.net/BrendanEich/metaprog-5303821#text-version


var sys = require("sys")





// ARRAY

var array = [1,2,3,4,5]

sys.puts("Every Element Less than 5? " + array.every(function(element, index, array) {
    return element < 5 
}))

sys.puts("Any element less than 5? " + array.some(function(element, index, array) {
    return element < 5 
}))

sys.puts(array.indexOf(2))
sys.puts(array.lastIndexOf(2))
sys.puts(array.filter(function(item) { return item > 3 }))
array.forEach(function(item) { sys.puts("FE " + item) })
sys.puts(array.map(function(item) { return item + 1}))
sys.puts("Sum: " + array.reduce(function(prev, curr) { return prev + curr })) // also reduceRight




// OBJECTS
sys.puts("OBJECTS")
var obj = {name:"value"}
sys.puts(Object.keys(obj))
sys.puts(Object.getOwnPropertyNames(obj)) // also non-enumerable property names

function Bob() {}
Bob.prototype = {something:"hi"}
sys.puts(Object.getPrototypeOf(new Bob()).something)


// DATES
sys.puts("DATES")
var date = new Date()
sys.puts(date.toISOString())
sys.puts(Date.parse("2010-01-01 12:00"))
sys.puts(new Date("2010-01-01 12:00")) // saweet!
sys.puts(Date.now()) // instead of (new Date()).getTime()



// STRING
sys.puts(" hello world   ".trim())






// WEIRDER OBJECT STUFF



var point = { x: 5, y: 8, get r() { return 3 } }

sys.puts(sys.inspect(Object.getOwnPropertyDescriptor(point, 'x')))
sys.puts(sys.inspect(Object.getOwnPropertyDescriptor(point, 'r')))

Object.defineProperty(point, 'z', {
    value: 0,               
    enumerable: true,       // shows up in for (var i in obj)?
    writable: false,        // disable obj.name = x 
    configurable: false     // diable delete obj.name
})

var point = Object.create(Object.prototype, {
    x: { value: 5 }, 
    y: { value: 8 },
    r: { get: function() { return 2 }, enumerable:true },
    z: { value: 0, enumerable: false },
    asdf: { value: function() {} } // a value can be a normal function
})

sys.puts(point.r)

Object.preventExtensions(point)
// point.woot = "hi" // throws an error!

Object.seal(point)
// delete point.x // throws an error!

Object.freeze(point)
// point.x = 7 // throws an error!


// This is a BAD example
function makePoint(x,y) {
    return {x:x, y:y}
}

function wrapPointWithLog(p) {
    return {
        get x() {
            sys.log('get x')
            return p.x
        },
        set x(v) {
            sys.log('set x')
            p.x = v
        }
        // etc
    }
}

var wrappedPoint = wrapPointWithLog(makePoint(1,2))
wrappedPoint.x
wrappedPoint.x = 4




// CLONE
Object.defineProperty(Object.prototype, "clone", {
    value: function(props) {
        return Object.create(this, props) // not sure
    }
})

var john = {
    name: "John",
    skill: "Javacsript"
}

var mike = john.clone({name: {value: "Mike"}})

sys.puts(mike.name)
sys.puts(mike.skill)

mike.name = "Bob"

sys.puts(mike.name)
sys.puts(john.name) // doesn't change john. 

















// HARMONY PROXIES - don't work :(
// This WOULD allow us to intercept missing methods and properties, etc. 
// function makeLogger(obj) {
//     var proxy = Proxy.create({
//         get: function(rcvr, name) {
//             sys.log("Got " + name)
//             return obj[name]
//         },
//         set: function(rcvr, name, val) {
//             sys.log("Set " + name)
//             obj[name] = val
//             return true
//         }
//     }, Object.getPrototypeOf(obj))
//     return proxy
// }

// var loggedPoint = makeLogger(point)
// sys.puts(ForwardingHandler)

// loggedPoint.x = 3