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ES.next
The document discusses new features coming to JavaScript in the future. It describes CoffeeScript and compiling ES.next to current JavaScript as ways to experiment with these new features. It lists some approved features for ES.next, including block scope variables, destructuring, default parameters, rest/spread syntax, proxies, weak maps, modules, and iterators/generators. The document also discusses goals for ES.next such as being better for complex apps, libraries, and code generators while keeping versions simple and supporting a secure subset.
ES.next
- 1. CoffeeScript, ES.next, theJS Language Lab mozilla 1 Wednesday, May 4, 2011
- 2. What you shouldexpect in the Future mozilla 2 Wednesday, May 4, 2011
- 3. What you shouldexpect in the Future • “No fate but what we make.” - Sarah Connor, T2 mozilla 2 Wednesday, May 4, 2011
- 4. What you shouldexpect in the Future • “No fate but what we make.” - Sarah Connor, T2 • “Leaders can imagine a world that others don’t. Like Thomas Jefferson or that kid in the Terminator movies.” - Finn, Glee mozilla 2 Wednesday, May 4, 2011
- 5. What you shouldexpect in the Future • “No fate but what we make.” - Sarah Connor, T2 • “Leaders can imagine a world that others don’t. Like Thomas Jefferson or that kid in the Terminator movies.” - Finn, Glee • How to invent the future: mozilla 2 Wednesday, May 4, 2011
- 6. What you shouldexpect in the Future • “No fate but what we make.” - Sarah Connor, T2 • “Leaders can imagine a world that others don’t. Like Thomas Jefferson or that kid in the Terminator movies.” - Finn, Glee • How to invent the future: • CoffeeScript (and all the languages targeting JS) mozilla 2 Wednesday, May 4, 2011
- 7. What you shouldexpect in the Future • “No fate but what we make.” - Sarah Connor, T2 • “Leaders can imagine a world that others don’t. Like Thomas Jefferson or that kid in the Terminator movies.” - Finn, Glee • How to invent the future: • CoffeeScript (and all the languages targeting JS) • Compile ES.next -> JS of today with a Harmonizr mozilla 2 Wednesday, May 4, 2011
- 8. What you shouldexpect in the Future • “No fate but what we make.” - Sarah Connor, T2 • “Leaders can imagine a world that others don’t. Like Thomas Jefferson or that kid in the Terminator movies.” - Finn, Glee • How to invent the future: • CoffeeScript (and all the languages targeting JS) • Compile ES.next -> JS of today with a Harmonizr • Keep iterating... mozilla 2 Wednesday, May 4, 2011
- 9. The Harmony goals mozilla 3 Wednesday, May 4, 2011
- 10. The Harmony goals • Be a better language for writing: mozilla 3 Wednesday, May 4, 2011
- 11. The Harmony goals • Be a better language for writing: • complex applications mozilla 3 Wednesday, May 4, 2011
- 12. The Harmony goals • Be a better language for writing: • complex applications • libraries (including the DOM) shared by those applications mozilla 3 Wednesday, May 4, 2011
- 13. The Harmony goals • Be a better language for writing: • complex applications • libraries (including the DOM) shared by those applications • code generators targeting the new edition mozilla 3 Wednesday, May 4, 2011
- 14. The Harmony goals • Be a better language for writing: • complex applications • libraries (including the DOM) shared by those applications • code generators targeting the new edition • Better tests, if not a testable (executable) specification mozilla 3 Wednesday, May 4, 2011
- 15. The Harmony goals • Be a better language for writing: • complex applications • libraries (including the DOM) shared by those applications • code generators targeting the new edition • Better tests, if not a testable (executable) specification • Adopt de facto standards where possible mozilla 3 Wednesday, May 4, 2011
- 16. The Harmony goals • Be a better language for writing: • complex applications • libraries (including the DOM) shared by those applications • code generators targeting the new edition • Better tests, if not a testable (executable) specification • Adopt de facto standards where possible • Keep versioning as simple and linear as possible mozilla 3 Wednesday, May 4, 2011
- 17. The Harmony goals • Be a better language for writing: • complex applications • libraries (including the DOM) shared by those applications • code generators targeting the new edition • Better tests, if not a testable (executable) specification • Adopt de facto standards where possible • Keep versioning as simple and linear as possible • Support a statically verifiable, object-capability secure subset mozilla 3 Wednesday, May 4, 2011
- 18. Approved for ES.next mozilla 4 Wednesday, May 4, 2011
- 19. Approved for ES.next • let, const, function in block scope mozilla 4 Wednesday, May 4, 2011
- 20. Approved for ES.next • let, const, function in block scope • destructuring: let {x, y} = pt; let [s, v, o] = triple() mozilla 4 Wednesday, May 4, 2011
- 21. Approved for ES.next • let, const, function in block scope • destructuring: let {x, y} = pt; let [s, v, o] = triple() • parameter default values: function f(x, y=1, z=0) {...} mozilla 4 Wednesday, May 4, 2011
- 22. Approved for ES.next • let, const, function in block scope • destructuring: let {x, y} = pt; let [s, v, o] = triple() • parameter default values: function f(x, y=1, z=0) {...} • rest, spread: function g(i, j, ...r) { return r.slice(i, j); } let a = [0,1,2,3], o = new any_constructor(...a) mozilla 4 Wednesday, May 4, 2011
- 23. Approved for ES.next • let, const, function in block scope • destructuring: let {x, y} = pt; let [s, v, o] = triple() • parameter default values: function f(x, y=1, z=0) {...} • rest, spread: function g(i, j, ...r) { return r.slice(i, j); } let a = [0,1,2,3], o = new any_constructor(...a) • proxies, weak maps: Proxy.create(handler, proto), new WeakMap mozilla 4 Wednesday, May 4, 2011
- 24. Approved for ES.next • let, const, function in block scope • destructuring: let {x, y} = pt; let [s, v, o] = triple() • parameter default values: function f(x, y=1, z=0) {...} • rest, spread: function g(i, j, ...r) { return r.slice(i, j); } let a = [0,1,2,3], o = new any_constructor(...a) • proxies, weak maps: Proxy.create(handler, proto), new WeakMap • modules: module M { export function fast_sin(x) {...} } mozilla 4 Wednesday, May 4, 2011
- 25. Approved for ES.next • let, const, function in block scope • destructuring: let {x, y} = pt; let [s, v, o] = triple() • parameter default values: function f(x, y=1, z=0) {...} • rest, spread: function g(i, j, ...r) { return r.slice(i, j); } let a = [0,1,2,3], o = new any_constructor(...a) • proxies, weak maps: Proxy.create(handler, proto), new WeakMap • modules: module M { export function fast_sin(x) {...} } • iterators, generators: function* gen() { yield 1; yield 2; } mozilla 4 Wednesday, May 4, 2011
- 26. Approved for ES.next • let, const, function in block scope • destructuring: let {x, y} = pt; let [s, v, o] = triple() • parameter default values: function f(x, y=1, z=0) {...} • rest, spread: function g(i, j, ...r) { return r.slice(i, j); } let a = [0,1,2,3], o = new any_constructor(...a) • proxies, weak maps: Proxy.create(handler, proto), new WeakMap • modules: module M { export function fast_sin(x) {...} } • iterators, generators: function* gen() { yield 1; yield 2; } mozilla • comprehensions: return [a+b for (a in A) for (b in B)] 4 Wednesday, May 4, 2011
- 27. Yet more approvedfor ES.next mozilla 5 Wednesday, May 4, 2011
- 28. Yet more approvedfor ES.next • Binary data: mozilla 5 Wednesday, May 4, 2011
- 29. Yet more approvedfor ES.next • Binary data: • const Point2D = new StructType({ x: uint32, y: uint32 }), Color = new StructType({ r: uint8, g: uint8, b: uint8 }), Pixel = new StructType({ point: Point2D, color: Color }); mozilla 5 Wednesday, May 4, 2011
- 30. Yet more approvedfor ES.next • Binary data: • const Point2D = new StructType({ x: uint32, y: uint32 }), Color = new StructType({ r: uint8, g: uint8, b: uint8 }), Pixel = new StructType({ point: Point2D, color: Color }); • const Triangle = new ArrayType(Pixel, 3); mozilla 5 Wednesday, May 4, 2011
- 31. Yet more approvedfor ES.next • Binary data: • const Point2D = new StructType({ x: uint32, y: uint32 }), Color = new StructType({ r: uint8, g: uint8, b: uint8 }), Pixel = new StructType({ point: Point2D, color: Color }); • const Triangle = new ArrayType(Pixel, 3); • new Triangle([{ point: { x: 0, y: 0 }, color: { r: 255, g: 255, b: 255 } }, { point: { x: 5, y: 5 }, color: { r: 128, g: 0, b: 0 } }, { point: { x: 10, y: 0 }, color: { r: 0, g: 0, b: 128 } }]); mozilla 5 Wednesday, May 4, 2011
- 32. Hot, but notyet in Harmony mozilla 6 Wednesday, May 4, 2011
- 33. Hot, but notyet in Harmony • Arrow function syntax, instead of λ, ƒ, or # (want to save # for later) mozilla 6 Wednesday, May 4, 2011
- 34. Hot, but notyet in Harmony • Arrow function syntax, instead of λ, ƒ, or # (want to save # for later) • Just like CoffeeScript: let identity = (x) -> x mozilla 6 Wednesday, May 4, 2011
- 35. Hot, but notyet in Harmony • Arrow function syntax, instead of λ, ƒ, or # (want to save # for later) • Just like CoffeeScript: let identity = (x) -> x • Expression body: const square = (x) -> (x * x) mozilla 6 Wednesday, May 4, 2011
- 36. Hot, but notyet in Harmony • Arrow function syntax, instead of λ, ƒ, or # (want to save # for later) • Just like CoffeeScript: let identity = (x) -> x • Expression body: const square = (x) -> (x * x) • Statement body: let countUsed = (str) -> { if (str in usedWords) usedWords[str]++; else usedWords[str] = 1; } mozilla 6 Wednesday, May 4, 2011
- 37. Hot, but notyet in Harmony • Arrow function syntax, instead of λ, ƒ, or # (want to save # for later) • Just like CoffeeScript: let identity = (x) -> x • Expression body: const square = (x) -> (x * x) • Statement body: let countUsed = (str) -> { if (str in usedWords) usedWords[str]++; else usedWords[str] = 1; } • Fat arrow too: callback = (msg) => ( this.vmail.push(msg) ) mozilla 6 Wednesday, May 4, 2011
- 38. Hot, but notyet in Harmony • Arrow function syntax, instead of λ, ƒ, or # (want to save # for later) • Just like CoffeeScript: let identity = (x) -> x • Expression body: const square = (x) -> (x * x) • Statement body: let countUsed = (str) -> { if (str in usedWords) usedWords[str]++; else usedWords[str] = 1; } • Fat arrow too: callback = (msg) => ( this.vmail.push(msg) ) • Binding forms: let f() -> “writable” const K() -> “readonly” mozilla 6 Wednesday, May 4, 2011
- 39. What else? mozilla 7 Wednesday, May 4, 2011
- 40. What else? • CoffeeScript classes, for prototypal inheritance sugar • Or a different classes as closure pattern sugar proposal? • Or (and this is somewhat Coffee-like) extended object initialisers? mozilla 7 Wednesday, May 4, 2011
- 41. What else? • CoffeeScript classes, for prototypal inheritance sugar • Or a different classes as closure pattern sugar proposal? • Or (and this is somewhat Coffee-like) extended object initialisers? • Coffee’s @foo for this.foo • Or some private names or “soft fields” @ usage? mozilla 7 Wednesday, May 4, 2011
- 42. What else? • CoffeeScript classes, for prototypal inheritance sugar • Or a different classes as closure pattern sugar proposal? • Or (and this is somewhat Coffee-like) extended object initialisers? • Coffee’s @foo for this.foo • Or some private names or “soft fields” @ usage? • Paren-free syntax: if x > y return x while i < n { a.push(i++); } mozilla 7 Wednesday, May 4, 2011
- 43. What else? • CoffeeScript classes, for prototypal inheritance sugar • Or a different classes as closure pattern sugar proposal? • Or (and this is somewhat Coffee-like) extended object initialisers? • Coffee’s @foo for this.foo • Or some private names or “soft fields” @ usage? • Paren-free syntax: if x > y return x while i < n { a.push(i++); } • More operators: ?? ??= div mod divmod is isnt mozilla 7 Wednesday, May 4, 2011
- 44. What’s going onhere? • Remember these Harmony goals: • Be a better language for writing: • complex applications • libraries (including the DOM) shared by those applications • code generators targeting the new edition • Adopt de facto standards where possible mozilla 8 Wednesday, May 4, 2011
- 45. Word of theday: Transpiler mozilla 9 Wednesday, May 4, 2011
- 46. Word of theday: Transpiler A transcompiler (also known as transpiler) is a special compiler that translates the source code of a programming language into the source code of another programming language, e.g. from Pascal to C. mozilla 9 Wednesday, May 4, 2011
- 47. Word of theday: Transpiler A transcompiler (also known as transpiler) is a special compiler that translates the source code of a programming language into the source code of another programming language, e.g. from Pascal to C. en.wikipedia.org/wiki/Transpiler mozilla 9 Wednesday, May 4, 2011
- 48. Word of theday: Transpiler A transcompiler (also known as transpiler) is a special compiler that translates the source code of a programming language into the source code of another programming language, e.g. from Pascal to C. en.wikipedia.org/wiki/Transpiler mozilla 9 Wednesday, May 4, 2011
- 49. Word of theday: Transpiler A transcompiler (also known as transpiler) is a special compiler that translates the source code of a programming language into the source code of another programming language, e.g. from Pascal to C. en.wikipedia.org/wiki/Transpiler • CoffeeScript, many others mozilla 9 Wednesday, May 4, 2011
- 50. Word of theday: Transpiler A transcompiler (also known as transpiler) is a special compiler that translates the source code of a programming language into the source code of another programming language, e.g. from Pascal to C. en.wikipedia.org/wiki/Transpiler • CoffeeScript, many others • Dave Herman’s module loaders for language polyfills mozilla 9 Wednesday, May 4, 2011
- 51. Word of theday: Transpiler A transcompiler (also known as transpiler) is a special compiler that translates the source code of a programming language into the source code of another programming language, e.g. from Pascal to C. en.wikipedia.org/wiki/Transpiler • CoffeeScript, many others • Dave Herman’s module loaders for language polyfills • Debuggable primary source support coming in Firefox mozilla 9 Wednesday, May 4, 2011
- 52. Word of theday: Transpiler A transcompiler (also known as transpiler) is a special compiler that translates the source code of a programming language into the source code of another programming language, e.g. from Pascal to C. en.wikipedia.org/wiki/Transpiler • CoffeeScript, many others • Dave Herman’s module loaders for language polyfills • Debuggable primary source support coming in Firefox mozilla 9 Wednesday, May 4, 2011
- 53. Back to Jeremy... mozilla 10 Wednesday, May 4, 2011