Matt Kruse's JavaScript Toolbox presents a number of excellent best practice ideas including: using var, feature detection, when to use square bracket notation, avoiding eval, referencing forms and form elements, avoiding the with keyword, using onclick instead of JavaScript pseudo-protocol, using unary + to type convert to numbers, avoiding document.all, not using HTML comments in script blocks, avoid cluttering the global namespace, avoiding prototype.js, avoiding synch Ajax calls, using JSON and the correct way to use script tags
Ryan Campbell shows how to get the Prototype library up and running, and introduces and documents Protoype's $() function. Form helper functions, getElementsByClassName functions, Element helper functions, Ajax support, timer functions are all covered.