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The moment (function(){})() made sense.

Let's start with a simple concept.

1 + 1
=> 2

Adding parens clarifies order of operations.

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JS Callback AH-HA

When I told people I was confused about callbacks I often heard that callbacks were just functions. So I couldn't figure out what my hurdle was to grasping them. But I just had an AH-HA! moment after getting a better grasp on some basic syntax.

JavaScript functions use () for two different reasons. Let me recap so that we're on the same page;

2 reasons for ( )

1st | Declaration

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JS return values chain well

Make an array

var a = []
=> []

And a function that returns the array

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Shorthand if, else if, else (and return)

Getting comfortable with the shorthand conditional syntax. If you put the conditional on one line, the {} are not needed. Even when having multiple conditionals.

Explicit returns

return will terminate the function and spit out as it sees. No need to assign the argument to a variable.

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JSON

The two methods to conver data.

JSON.stringify JSON.parse

var user = JSON.stringify({name: 'dave', age: 1977, occupation: 'developer'});
user;

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map (as well as forEach, filter, and similar array methods) passes a second argument to the function it is given: the index of the current element.

forEach

filter

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Learning javascript's map() and other magic.

Map returns the value of an array, as a new array.

In my quest to learn it, I went to mozialla and found the explaination unclear. I started playing around with it to learn it.

var pets = ['cat', 'dog', 'mouse', 'bird']
var more_pets = pets.map(function(value){
return value;
})

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function reduce(array, start, callback) {
  // javascript, and all of programming often needs variables to contain state.
  var current = start, 
      freq = array.length; 
      

  for (var i = 0; i < freq; i++){
    // how much of learning is problem solving vs. syntax?
 current = callback(current, array[i]); 

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Notes from Eloquent JavaScript

Object

grasp this

defineProperty()

Object.create()

Why use Object.create verse just normal {}?

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Notes from Eloquent JavaScript

Recall that the apply and bind methods both take a first argument that can be used to simulate method calls. This first argument is in fact used to give a value to this.

There is a method similar to apply, called call. It also calls the function it is a method of but takes its arguments normally, rather than as an array. Like apply and bind, call can be passed a specific this value.

speak.apply(fatRabbit, ["Burp!"]);
// → The fat rabbit says 'Burp!'
speak.call({type: "old"}, "Oh my.");