This is the first post of a series of Javascript re-learn posts. Why am I writing it when there are some many similar stuff out on Internet? If there has to be a reason, the first one would be to review my knowledge on Javascript and hopefully I can get some level of “学而时习之,可以为师矣”.

Types

One of the best ways to learn a programming language is to think like I’m going to design it.

Just like the natural languages, first we need to properly express the things in nouns, like apple, orange, etc. As an advanced programming language, Javascript’s types are properly designed, not too simple not too complex.

It starts with Number, then String and Boolean. Then a little more complex, Object and Function. And that’s all, not too overwhelming for beginners to start with.

Number

Rather that some other languages, e.g. Java, with which the programmer has to remember Integer, Long, Float, Double, BigDecimal and BigInteger, etc, Javascript relieves the beginners from this burden. All numbers start with Type Number.

String

After much pain with C, most programming language designers have added String as a primitive type ever since, which is proved to be the very right thing to do.

Boolean

Boolean is not necessary to be a primitive, e.g. C. But defining a Boolean type has been well accepted. It makes the readability of the program better. see following negative example:

int a = 0; 

//Then change a to some other value

if (a) { // do something if expression "a" is true
  //do something
}

To be honest, after so many years, I still have to google to find out whether 0 is true or non-0 is true.

Object

When Javascript is designed, OOP is already well accepted. So the author adopted some OOP into the language. But probably he doesn’t like the complexities of OOP – classes, interfaces, abstract classes, inheritance, etc. So he just pick one very simple concept, the Object, to express all the different real life things, just like he picked only Number to express all the numbers.

Function

Imagine (脑洞大开) the first human beings who invented the word “apple”, then they can use it communicate with their peers. But soon after that, they would have the need to express “pick” and “eat”.

In the programming languages, “pick” and “eat” are functions. Once programmers have objects, they would need functions to operate on the objects. Unlike some languages like Java (sorry), Javascript’s functions can work independently. They are first-class citizens just like objects. This little difference opens the door for Javascript to become a proper player in the functional programming area.

Javascript the types (Nouns and Verbs)

Contents