Small Overview on JavaScript

JavaScript is a high-level programming language that is multi-paradigm, dynamic with types and operators, standard built-in objects, and methods. Its syntax is based on C language and Java. JavaScript support object-oriented programming with object prototype.

JavaScript types are:

o Number

o String

o Boolean

o Object

· Function

· Array

· Date

· RegExp

o Symbol

o Undefine

o Null

In JavaScript, there are some built-in error types.

Variables

In JavaScript, there are used let, const, and var to declared variables.

let allow us to declare block-level variables and the value of the declared variable can be changed.

const allows us to declare a variable which values are never changed.

var is the most common keyword to use declared a variable. It doesn’t have any restrictions that the other two keywords have.

Operators

Numeric Operator:

  • , -, *, / and %

Comparison Operator:

<, >, >=, <=

There are != and !== operators also.

Objects

In JavaScript, objects can be a collection of name-value pairs. They are similar to:

o Dictionaries in Python

o Hashes in Perl and Ruby

o Hash table in C and C++

o HashMap’s in Java

o Associative arrays in PHP.

Since everything in JavaScript is an object, any JavaScript program naturally involves a great deal of hash table lookup. It’s a good thing that they are so fast!

There is two basic way to create an empty object:

Arrays

Arrays in JavaScript are special types of objects. In one array we can put many objects. And we can see the lengths of the objects in an array by using property-name.length

Function

Along with the objective function is the core component in understanding JavaScript. A JavaScript function can take 0 or more named parameters. The function body can take more local variables and statements as we declared. The return statement can return a value at any time. The function can terminate if there is no return statement.

About Some String Prototype

charAt()

The string object’s charAt() located a specified object into a string and return a new object.

concat()

The concat() method concatenates the string and returns a new string.

If the argument values are not strings, they should be converting string values before concatenating.

includes()

This method performs a case-sensitive search to found a new string within another string.

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