By: Daniel Henneberger

 Introduction  Data Types  Flow Control  Inheritance/Built-in Functions  User defined types, Generics  Arrays  Function methods  Quirks  Comparison

  Prototype-based scripting language  Interpreted?  Chrome V8 attempts to compile  Java’s Rhino attempts to compile to byte code  Mozilla attempts JIT  Garbage Collection – Up to implementer  Loosely-typed, First-class functions, dynamic  Java-like syntax  Two Subsets  Default Language (will be abandon later)  Strict Language  Free  The word JavaScript must be licensed by Oracle  Mozilla has ‘Inventor rights’ Brief

  Developed for client-side processing on web browsers  Now capable of other tasks  Web Servers (node.js)  Desktop Widgets  Inside Applications Applications

  Originally Called LiveScript  Created for Netscape Navigator by Brendan Eich  Renamed JavaScript  Most likely a marking ploy  Microsoft created Jscript  Formalized to ECMAScript  ISO/IEC  ECMAScript v2  ECMAScript v3 History of JavaScript

  – ECMAScript v4 (Abandoned)  Google’s V8 Engine  Node.js created  ECMAScript v5  Test262 created  ISO/IEC 16262:2011  ECMAScript v5.1 History of JavaScript

  2013 – Java 8’s JavaScript Engine (Nashorn)  201? ECMAScript v6  Only strict mode  Incompatible syntax  Classes  Getters/Setters  Tamper proof objects  Block Scoping Future of JavaScript

  Adobe, Mozilla, Microsoft  Later came IBM, Google, Apple, Opera, Dojo, and Company 100. ECMAScript Committee

 CodenameBrowserTest262 Fail Percent JscriptMicrosoft Internet Explo. 95.2% SpiderMonkeyFirefox1.5% FutharkOpera0.1% V8Chrome0.1% Implementations Test262 really important

  End of line semicolons optional  Automatically inserted by compiler  Excess whitespace and comments are discarded during lexical analysis  Strings can be defined by ' or "  Multiline Strings possible with \ Grammar

 Introduction  Data Types  Flow Control  Inheritance/Built-in Functions  User defined types, Generics  Arrays  Function methods  Quirks  Comparison

  var - has functional scoping  const  null  undefined  let has block scoping ( ECMAScript v6 )  let and const to replace var Usable Types

  Undefined - primitive value used when a variable has not been assigned a value  Null - no value  Boolean – true/false  Number - double-precision 64-bit  NaN, Positive Infinity, Negative Infinity  IEEE 754  String - UTF-16  Object  runtime system performs automatic type conversion as needed  1+true=2, null + false = 0, null != false, null == undefined  Type coercion – new Boolean(true); Internal Types

 Introduction  Data Types  Flow Control  Inheritance/Built-in Functions  User defined types, Generics  Arrays  Function methods  Quirks  Comparison

 Flow Control - Sequencing function test(){ for( var i = 0; i<10; i++){ //doSomething; } return i; } result is 10

  if ( Expression ) Statement else Statement  if ( Expression ) Statement  SwitchStatement: switch ( Expression ) CaseBlock  CaseBlock:  { CaseClause }  { CaseClause DefaultClause CaseClause }  CaseClause: case Expression : StatementList  Default Clause: default : StatementList  with( Expression ) Statement  LogicalORExpression ? AssignmentExpression : AssignmentExpression Flow Control – Selection

  Simple Assignment: =  Compound Assignment: op= *= /= %= += -= >= >>>= &= ^= |=  Comma Operator (, ) Flow Control – Expression Evaluation

  do Statement while ( Expression );  while ( Expression ) Statement  for ( ExpressionNoIn ; Expression ; Expression ) Statement  for ( var VarDeclaration ; Expression ; Expression ) Statement  for ( LeftHandSideExpression in Expression ) Statement  for ( var VariableDeclarationNoIn in Expression ) Statement  label, break, continue, (throw, return, ‘normal’) Flow Control – Iteration

  function Identifier ( ParameterList ) { FunctionBody }  function ( ParameterList ) { FunctionBody } function square(y){ this.rslt = y*y; } var x = new square(5); x.rslt; var square = new Function("a", "b", "return a*b") Flow Control – Procedural Abstraction var x = function(y) { return y * y; }; x(5); function square(y){ return y*y; } square(5); var Math = { square: function(y){ return y*y } Math.square(5);

  Object Properties Flow Control – Procedural Abstraction Object.defineProperty(o, "a", { value : 37, writable : true, enumerable : true, configurable : true, get : function(){ return bValue; }, set : function(newValue){ bValue = newValue; } });

  No optimization for Tail Call Recursion  No concurrency  setTimeout(func, delay, [params])  setInterval()  new Worker(“something.js”) Flow Control – Recursion/Concurrency

  try / catch  try / finally  try / catch / finally  try { Code } catch ( Identifier ) {Code} finally {Code}  throw  Error, EvalError, RangeError, ReferenceError, SyntaxError, TypeError and URIError Flow Control – Exception Handling

  Global - variables that are not declared but are referenced are automatically global  Eval  Strict Mode- cannot return variables  Creates a new binding  Function  function x(){t = 5}; x(); console.log(t) //5  function x(){var t = 5}; x(); console.log(t) //undef Execution Context

 Introduction  Data Types  Flow Control  Inheritance/Built-in Functions  User defined types, Generics  Arrays  Function methods  Quirks  Comparison

 function Person(){} function Ninja(){} Ninja.prototype = new Person(); (new Ninja()) instanceof Person var o = new Object(); o.[[Prototype]] = Foo.prototype; o.Foo(); Prototype Based Inheritance

  Number  parseInt()  parseFloat()  parseInt()  isNaN()  ifFinite()  eval()  Library  Math  JSON  Date  RegExp  Special Characters  decodeURI  encodeURI Built-in Functions

 Introduction  Data Types  Flow Control  Inheritance/Built-in Functions  User defined types, Generics  Arrays  Function methods  Quirks  Comparison

user defined types generics  NONE!

 Introduction  Data Types  Flow Control  Inheritance/Built-in Functions  User defined types, Generics  Arrays  Function methods  Quirks  Comparison

  new Array([item1, item2, …])  new Array(len)  Keys can be integers or strings  Can be treated as: Arrays, Queues, Stacks, Priority Queues, Set  No bounds  arr[arr.length] = I; Arrays

  push  pop  reverse  sort  sort(function)  shift  slice  splice  unshift  indexOf  every  lastIndexOf  some(function)  forEach(function)  map(function)  filter(function)  reduce(function)  reduceRight(function) Array Operations

 x = 42; // creates the property x on the global object var y = 43; // declares a new variable, y myobj = {}; myobj.h = 4; // creates property h on myobj myobj.k = 5; // creates property k on myobj delete x; // returns true (x is a property of the global object and can be deleted) delete y; // returns false (delete doesn't affect variable names) delete Math.PI; // returns false (delete doesn't affect certain predefined properties) delete myobj.h; // returns true (user-defined properties can be deleted) with(myobj) { delete k; // returns true (equivalent to delete myobj.k) } delete myobj; // returns true delete

 Introduction  Data Types  Flow Control  Inheritance/Built-in Functions  User defined types, Generics  Arrays  Function methods  Quirks  Comparison

  bind() is powerful  x.bind(this);  call() – allows calling inner functions with current bindings  toString() Built-in Function Functions

 Introduction  Data Types  Flow Control  Inheritance/Built-in Functions  User defined types, Generics  Arrays  Function methods  Quirks  Comparison

  Floating point arithmetic IEEE 754  !== 0.3  A bad choice  All implementations see to behave differently  Code not portable  Accidental scoping  Global variables  var a = 0 || "4";  a = "4“  Scope hoisting  eval() Quirks

 Introduction  Data Types  Flow Control  Inheritance/Built-in Functions  User defined types, Generics  Arrays  Function methods  Quirks  Comparison

 JavaScriptJavaCGo Type Loosely Typed Strongly Typed Inheritance PrototypalClassical Automatic Multiple Inheritance No Yes Generics NoYesNo Pointers NoYesNoYes Closures YesNo Yes Exceptions Yes NoBuilt-in Threads NoYes Garbage Collection Yes NoYes Semi-Colon Optional YesNo Yes Like JavaScript 100%30% 40%

“Java and Javascript are similar like Car and Carpet are similar.” Greg Hewgill

 /publications/files/ECMA-ST/Ecma-262.pdf References