JavaScript basics quick recap

JavaScript basics quick recap

JavaScript basics mindmap

1. Basics 

- Earlier known as LiveScript and then later changed into JavaScript by NetScape.

- Invented by Brendan Eich.

#1.1 ) Definition

- JavaScript (JS) is a popular client side scripting language. Client side scripting means all code get executed in the client's computer.
- It is an interpreted language, that means it does not need to be compiled.
- We can use JS to change the appearance of Web page like animation, effects on Webpage and interactive pages.
- It has many uses like Form Validations, Highly responsive interfaces such as interactive maps, animated 2D / 3D graphics, etc.

#1.2 )  Pros and Cons

[1] Pros
-  It is the first lambda language to go mainstream.
-  It is the language of the web browser.
-  It is lightweight and expressive.
- JavaScript has a very powerful object literal notation. Objects can be created simply by listing their components.
-  JavaScript is a loosely typed language, so JavaScript compilers are unable to detect type errors.

[2] Cons
-  JavaScript depends on global variables for linkage.

2) Grammar

#2.1) Whitespace
- It is used to separate sequences of characters that would otherwise be combined into a single token.
- Types of whitespace are :-
1. tab
2. space
3. line end
4. Comments
1.  block comments formed with /* */
2.  line-ending comments starting with //

#2.2) Names
- A name is a letter optionally followed by one or more letters, digits, or underbars.
- Names are used for statements, variables, parameters, property names, operators, and labels.
- A name cannot be a reserved word.

#2.3) Numbers
- JavaScript has a single number type. Internally, it is represented as 64-bit floating point, the same as Java's double that means  1 and 1.0 are the same value in JavaScript.

#2.4) Strings

- A string literal can be wrapped in single quotes or double quotes. It can contain zero or more characters.

- Strings are immutable that is once made, a string can never be changed. But it is easy to make a new string by concatenating other strings together with the + operator.  Two strings containing exactly the same characters in the same order are considered to be the same string that means,

'g' + 'i' + 'f' + 't' === 'gift'

- Strings have methods.

-  JavaScript does not have a character type. To represent a character, make a string with just one character in it.
- Strings have a length property. Example :  "five".length is 4.

To get the complete Mindmap diagram Click this link.