Metaprogramming JavaScript
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JavaScript allows for metaprogramming through manipulating programs as data. It relies on few but powerful constructs including working with functions, arguments, built-in types, and mechanisms like inheritance at runtime. The key building blocks are objects, numbers, strings, booleans, and undefined, with everything else being objects. Functions are objects that can return other functions, taking advantage of closures to refer to outer variables from inner functions. This flexibility allows for patching implementations, self-optimizing code, custom APIs, and domain-specific languages.
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Metaprogramming JavaScript
- 1. Metaprogramming JavaScript Dan Webb (dan@danwebb.net)
- 2. What? “ the writing of computer programs that write or manipulate other programs (or themselves) as their data”
- 3. With JavaScript?! ★ Small and fiesty but widely misunderstood ★ Relies on few but powerful constructs ★ You can work with functions, arguments, built-ins types and mechanisms like inheritance at runtime ★ Techniques underpin many JS libraries
- 4. JavaScript Exposed: Objects Out Of Control!
- 5. Play along!
- 7. (Nearly) everything is a hash
- 8. number string boolean undefined
- 9. everything else is an Object
- 11. This works with any object
- 13. Expandos: a special case
- 20. Inspecting types
- 24. Wha?!
- 29. 'Methods' are just functions that are assigned to a property of an object
- 38. arguments
- 42. Functions can return other functions
- 45. Closure
- 46. Back to wikipedia... “ A closure occurs when a function is defined within another function, and the inner function refers to local variables of the outer function.
- 49. Why is that useful?
- 53. Functions can be used to make objects
- 55. Constructor functions are just functions
- 56. The magic is in the new operator
- 60. inheritance
- 67. The point is: its all just functions, objects and properties
- 68. We can hack it all.
- 69. So what can you do with this stuff?
- 70. Patch holes in bad implementations
- 76. Pretty APIs
- 79. Domain Specific Languages
- 85. John Resig's method overloading http://ejohn.org/blog/javascript-method-overloading/
- 89. Prototype 1.6 Classes http://prototypejs.org/learn/class-inheritance
- 92. and a lot more...
- 93. Looking back... ★ JavaScript is small but totally flexible ★ A handful of techniques provide everything you need ★ It's all about objects, properties and functions ★ Don't worry if its not all sunk in. Have a play around. Slides will be available.
- 94. Coming Soon...