WDC 1.9 ecmascript 6 better js for the ambient webera

the ambient of computing era

- corporate - cobol, fortran

- personal - c++ family

- ambient - javascript

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why js?

coz worse is better

- already there

- widest reach

- lowest risk

- write libs and apps once

- single knowledge and skillset

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is it even possible to replace it?

how does js evolved?

invented in 10 days in may 1995

mocha- livescript- js

javascript cloned in microsoft ie3.0 jscript

standarization ecma scrjpt

called ecma becuse java is sun., js is microsoft

so use ecma for none owner naming

-- ecmascript?

ecmascript is the standard that define javascript

not part of w3c

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js implementation

- google v8

- mozila spidermonkey

- microsoft chakra

- webkit jscore

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2009 ecmascript 5 :

use strict - json, object.create, etc

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2008 javascript performance problem.

2013 performance improved

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2014 es6 almost done,

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es6 improvement

- more concise syntax

modules and sandkng boxing

class declaration

control abstraction

array comprehensions

promises

string interpolations

subclasses

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tc39 its not like this..

and not like this..

google, ms, fb, netflix, safarj, jquery, ebay, yahoo, ie, intels

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ecma design challenges

the closure in loop problem

foreach() objcallback(x)

obj.callback(x) 

x will take the last.

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local scoping WTF

function(x,x)

var x

function x()

x()

so what x will be?

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why u need to worry about the edgecases?

because it will work on the browser but not on other browser

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how we fix?

closire in loop?

instead var using let

let p in x

let v = doSomethjbg (x,p)

let will binding on scope variable

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but want to avoid new let WTF

let x = 1

let x = 2

or 

let x =

var x = 

the solution, there will static error.

anybody shouldn't code this things.

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avoid inconsistent scoping WTF?

let x = 1

functionf ()

console log (x)

let x = 2

what will u get 1/ undefined / 2?

- never leaking scope.

avoid bogus const

using const x = 3

will be an error

-- but u need it in forward declaration

e.g mutual function

r1 = f(r2)

r2 = f(r1)

error vased upon time of actual access

nor upon position in source code

must be intialize before

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what abt block scope function?

function g()

g()

browser agree it will applied after it declared

but also disageee how to handle if g is not declare and call on the top or in the block or outside the block

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unfortunately browser agree violate block scoping

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summary

its real

will be the future soon