A statically-typed language is a language (such as Java, C, or C++) where variable types are known at compile time. In most of these languages, types must be expressly indicated by the programmer; in other cases (such as OCaml), type inference allows the programmer to not indicate their variable types
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Dynamically Typed Language
A language is dynamically-typed if the type of a variable is checked during run-time. Common examples of dynamically-typed languages includes JavaScript, Objective-C, PHP, Python, Ruby, Lisp, and Tcl.
avaScript is a dynamically typed language. In a dynamically typed language, the type of a variable is checked during run-time in contrast to statically typed language, where the type of a variable is checked during compile-time.
NaN Property JavaScript
NaN property represents “Not-a-Number” value. It indicates a value which is not a legal number.
typeof of a NaN will return a Number .
To check if a value is NaN, we use the isNaN() function
Implicit Type Coercion Javascript
Implicit type coercion in javascript is automatic conversion of value from one data type to another. It takes place when the operands of an expression are of different data types.
String coercion
String coercion takes place while using the ‘ + ‘ operator. When a number is added to a string, the number type is always converted to the string type.
When JavaScript sees that the operands of the expression x + y are of different types ( one being a number type and the other being a string type ) , it converts the number type to the string type and then performs the operation. Since after conversion, both the variables are of string type, the ‘ + ‘ operator outputs the concatenated string “33” in the first example and “24Hello” in the second example.
Hoisting Javascript
Hoisting is a default behaviour of javascript where all the variable and function declarations are moved on top.
This means that irrespective of where the variables and functions are declared, they are moved on top of the scope. The scope can be both local and global.
Data Types Javascript
There are two types of data types
Primitive types
String – It represents a series of characters and is written with quotes. A string can be represented using a single or a double quote.
Number – It represents a number and can be written with or without decimals.
BigInt – This data type is used to store numbers which are above the limitation of the Number data type. It can store large integers and is represented by adding “n” to an integer literal.
Boolean – It represents a logical entity and can have only two values : true or false. Booleans are generally used for conditional testing.
Undefined – When a variable is declared but not assigned, it has the value of undefined and it’s type is also undefined.
Null – It represents a non-existent or a invalid value.
Symbol – It is a new data type introduced in the ES6 version of javascript. It is used to store an anonymous and unique value.
To know the type of a JavaScript variable, we can use the typeof operator.
typeof “PHPCodez” // Returns “string”
typeof 7.14 // Returns “number”
typeof true // Returns “boolean”
Non-primitive types
Primitive data types can store only a single value. To store multiple and complex values, non-primitive data types are used.
Object – Used to store collection of data.
openvpn3 disconnect session
openvpn3 sessions-list
openvpn3 session-manage –session-path /net/openvpn/v3/sessions/f736b9easd8c0s4b5esb87ds1de3be2a29bc –disconnect
start openvpn centos 7
openvpn3 session-start –config /FOLDERPATH/client.ovpn
size of folder in linux terminal
du -hs FOLDERPATH/* will help to understnd which folder taken more disk space
/var/crash/ files
They are crash dumps of the kernel, i.e. files that contains useful information to recover the state of the kernel when it was crashing. These files are for your kernel what core dumps are for ordinary executables. There exists an utility that can be used to analyze those files : crash
You can delete files in under /var/crash if you’re willing to lose useful information needed to debug those crashes.