JavaScript Checklist

JS bits that are essential or worth getting familiar with.
List is open and if you feel something is missing, feel free to update it by forking it on GitHub.

Variables

• defining variables (default value, var and let operators)
• variable scopes (local and global, block in ECMAScript6)
• variable hoisting Adequately Good - JavaScript Scoping and Hoisting
• undefined vs null

Operators

• operators precedence
• how + behaves on strings and numbers
• || and && Web Reflection - Please Stop Reassigning For No Reason!
• real life usage for bitwise operators | ~, ~~, >>>
• typeof vs instanceof

Objects

• global object in browser and in strict mode
• built-in objects vs string literals
• securing the objects with ECMA5 methods

Arrays

• iterating
• for...in vs for
• ECMA5 methods map, filter, forEach, each, some, reduce, reduceRight
• removing elements from array (splice method vs delete)
• difference between array literals and object literals

Functions

• defining (difference between function foo(){} and var foo = function(){})
• invoking (as function, as method, as constructor, call/apply, bind (ECMA5))
• default return value and constructor return value
• arguments - the array-like object (not an array!)
• arguments.length vs functionName.length
• function context - this!
• the _this/that/self pattern
• closures!

JSON

• a subset of JS? JSON: The JavaScript subset that isn’t

Inheritance

• prototype object and prototype chain
• constructors and difference between fun() and new fun()

Browsers and DOM

• memory leaks in browsers
• compilers

Script loading

• asynchronous/deferred script loading
• scripts concatenation

Events

• DOM events bubbling and capturing Quirksmode - Event order
• cancelable events
• event delegation
• custom events

Event loop

• timers, setInterval, setTimeout, how to use them

Misc

• how eval works
• design patterns in JS Adequately Good - JavaScript Module Pattern: In-Depth Essential JavaScript Design Patterns For Beginners, Volume 1
• memory management Socialcast Engineering - JavaScript Memory Management

Reference