Douglas Crockford’s Google Talk – JavaScript: The Good Parts

My notes from Douglas Crockford’s Google Talk based on his book, JavaScript: The Good Parts.

• JavaScript is misunderstood
• DOM is source of poor performance, not JS
• If you’re going to use a language, learn it… JS is easy to use without learning it and that’s a cause for misunderstanding it
• JS is loosely typed
• Amount of testing required in Java and JS is about the same… the type checking happens through the tests
• You don’t have to worry about type checking
• bad parts:  global variables; + adds and concatenates; semicolon insertion; typeof; with and eval; phony arrays; == and !=; false, null, undefined, NaN
• arrays are hashtables with indexes as keys
• always use ===, never use ==
• if you ask for a property that doesn’t exist, you get undefined
• bad heritage:  blockless statements; expression statements; floating point arithmetic; ++ and –; switch
• DC doesn’t use ++ and —
• good parts: lambda, dynamic objects, loose typing, object literals
• two schools of inheritance:   classical (most OO languages), prototypal (JS)
• prototypal inheritance: class free; objects inherit from objects; an object contains a link to object to inherit from
• “new” operator is required when calling a Constructor function… dangerous and DC doesn’t use it anymore
• function variable scope, but no block variable scope
• create objects using closures
• start block statements on the same line as the declaration… semicolon insertion will rear its ugly head
• “Working with the Grain”
• JSON derived from the good parts of JS
• JS is really based on Scheme
• JSLint identifies the bad parts — do everything it says, it’s smarter about JS than you are
• If you avoid the bad parts, JS works really well — it is possible to write good programs in JS