JavaScript – Hive

rinoymjosephDecember 13, 2018December 13, 2018

TypeORM Express Application Using Repository Pattern – Part 4 – How to do Cascade Save

In Part 2 of this series, we have seen how to persist data if we have a parent child relationship between tables. In this post we discuss about cascade save….

rinoymjosephDecember 12, 2018December 13, 2018

TypeORM Express Application Using Repository Pattern – Part 3 – How to perform InnerJoin

rinoymjosephDecember 11, 2018December 13, 2018

TypeORM Express Application Using Repository Pattern – Part 2 – Persist Data into Tables

This is the second part of the tutorial on developing a NodeJS application which uses Express, TypeORM and MySQL Server for data persistence. The benefit of using TypeORM for the…

rinoymjosephDecember 10, 2018

How to Integrate Angular 6/7 application with TypeORM and Express

rinoymjosephDecember 10, 2018December 13, 2018

TypeORM Express Application Using Repository Pattern – Part 1 – Create Tables with Relationships

This tutorial explores how we can create a Node.js application written in TypeScript and connect to a MySQL database using TypeORM package. It also gets into advanced topics like joins…

rinoymjosephSeptember 27, 2017September 27, 2017

TypeScript Web Application using Angular4, NodeJS, Express and MySQL – Part 1

rinoymjosephSeptember 25, 2017December 13, 2018

Creating a TypeScript NodeJS Express App using TypeORM and MySQL – Part2

This tutorial is the second part of ‘Creating a TypeScript NodeJS Express App using TypeORM and MySQL’. The first part is accessible in below link. Please read first part to understand…

rinoymjosephSeptember 25, 2017December 13, 2018

Creating a TypeScript NodeJS Express App using TypeORM and MySQL – Part1

This tutorial explores how we can create a Node.js application written in TypeScript and connect to a MySQL database using TypeORM package. TypeORM is an Object Relational Mapper (ORM) for Node.js written…

rinoymjosephJuly 27, 2017July 27, 2017

Scope of variables in JavaScript

1) Global Scope

var a = 1;

// global scope
function one() {
  alert(a); // alerts '1'
}

var a = 1;

// global scope

function one() {

alert(a); // alerts '1'

}

2) Local scope

var a = 1;

function two(a) {
  alert(a); // alerts the given argument, not the global value of '1'
}

// local scope again
function three() {
  var a = 3;
  alert(a); // alerts '3'
}

var a = 1;

function two(a) {

alert(a); // alerts the given argument, not the global value of '1'

}

// local scope again

function three() {

var a = 3;

alert(a); // alerts '3'

}

3) Block Scope a) No block scope in JavaScript till ES6.

var a = 1;

function four() {
  if (true) {
    var a = 4;
  }

  alert(a); // alerts '4', not the global value of '1'
}

var a = 1;

function four() {

if (true) {

var a = 4;

}

alert(a); // alerts '4', not the global value of '1'

}

b) ES6 introduced let

var a = 1;

function one() {
  if (true) {
    let a = 4;
  }

  alert(a); // alerts '1' because the 'let' keyword uses block scoping
}

var a = 1;

function one() {

if (true) {

let a = 4;

}

alert(a); // alerts '1' because the 'let' keyword uses block scoping

}

4) Intermediate: Object properties

var a = 1;

function five() {
  this.a = 5;
}

alert(new five().a); // alerts '5'

var a = 1;

function five() {

this.a = 5;

}

alert(new five().a); // alerts '5'

5) Advanced: Closure

var a = 1;

var six = (function() {
  var a = 6;

  return function() {
    // JavaScript "closure" means I have access to 'a' in here,
    // because it is defined in the function in which I was defined.
    alert(a); // alerts '6'
  };
})();

var a = 1;

var six = (function() {

var a = 6;

return function() {

// JavaScript "closure" means I have access to 'a' in here,

// because it is defined in the function in which I was defined.

alert(a); // alerts '6'

};

})();

6) Advanced: Prototype-based…

rinoymjosephJuly 27, 2017July 27, 2017

Write a basic Object Oriented JavaScript class

function MyClass () { // constructor function
  var privateVariable = "foo";  // Private variable 

  this.publicVariable = "bar";  // Public variable 

  this.privilegedMethod = function () {  // Public Method
    alert(privateVariable);
  };
}

// Instance method will be available to all instances but only load once in memory 
MyClass.prototype.publicMethod = function () {    
  alert(this.publicVariable);
};

// Static variable shared by all instances
MyClass.staticProperty = "baz";

var myInstance = new MyClass();

function MyClass () { // constructor function

var privateVariable = "foo"; // Private variable

this.publicVariable = "bar"; // Public variable

this.privilegedMethod = function () { // Public Method

alert(privateVariable);

};

}

// Instance method will be available to all instances but only load once in memory

MyClass.prototype.publicMethod = function () {

alert(this.publicVariable);

};

// Static variable shared by all instances

MyClass.staticProperty = "baz";

var myInstance = new MyClass();