Tag Archives: PHP

Javascript

Scope Javascript

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Scope in JS, determines the accessibility of variables and functions at various parts in one’s code.

In general terms, the scope will let us know at a given part of code, what are the variables and functions that we can or cannot access.

There are three types of scopes in JS:

Global Scope
Local or Function Scope
Block Scope

Global Scope

Variables or functions declared in the global namespace have global scope, which means all the variables and functions having global scope can be accessed from anywhere inside the code

Function Scope

Any variables or functions declared inside a function have local/function scope, which means that all the variables and functions declared inside a function, can be accessed from within the function and not outside of it.

Block Scope

Block scope is related to the variables declared using let and const. Variables declared with var do not have block scope.

Block scope tells us that any variable declared inside a block { }, can be accessed only inside that block and cannot be accessed outside of it.

Javascript

Higher Order Functions Javascript

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In Javascript, functions can be assigned to variables in the same way that strings or arrays can. They can be passed into other functions as parameters or returned from them as well. A “higher-order function” is a function that accepts functions as parameters and/or returns a function.

Functions that operate on other functions, either by taking them as arguments or by returning them, are called higher-order functions.

Higher order functions are a result of functions being first-class citizens in javascript.

Javascript

Dynamically Typed Language

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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.

Javascript

Implicit Type Coercion Javascript

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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.