Node Programming Examples

ES6 Miscellaneous Operators

node

var x = 4 
var y = -x; 
console.log("value of x: ",x); //outputs 4 
console.log("value of y: ",y); //outputs -4

ES6 let v/s var

node

var no = 10; 
var no = 20; 
console.log(no);

ES6 Let and Block Scope

node

"use strict" ;
function test() { 
   var num = 100;
   console.log("value of num in test() " + num); { 
      console.log("Inner Block begins") 
      let num = 200; 
      console.log("value of num : "+num)  
   } 
} 
test()

ES6 Custom Error with user-defined error message

node

function MyError(message) { 
   this.name = 'CustomError'; 
   this.message = message || 'Default Error Message';  
} try { 
   throw new MyError('Printing Custom Error message'); 
} 
catch (e) { 
   console.log(e.name);      
   console.log(e.message);  
}

ES6 Custom Error with default message

node

function MyError(message) { 
   this.name = 'CustomError'; 
   this.message = message || 'Error raised with default message'; 
} 
try { 
   throw new MyError(); 
} catch (e) {  
   console.log(e.name);      
   console.log(e.message);  // 'Default Message' 
}

ES6 Exception Handling

node

var a = 100; 
var b = 0; 
try { 
   if (b == 0 ) { 
      throw("Divide by zero error."); 
   } else { 
      var c = a / b; 
   } 
} 
catch( e ) { 
   console.log("Error: " + e ); 
}

ES6 Super Keyword

node

'use strict' 
class PrinterClass { 
   doPrint() {
      console.log("doPrint() from Parent called…") 
   } 
}  
class StringPrinter extends PrinterClass { 
   doPrint() { 
      super.doPrint() 
      console.log("doPrint() is printing a string…") 
   } 
} 
var obj = new StringPrinter() 
obj.doPrint()

ES6 Class Inheritance and Method Overriding

node

'use strict' ;
class PrinterClass { 
   doPrint() { 
      console.log("doPrint() from Parent called… ");
   }
}
class StringPrinter extends PrinterClass { 
   doPrint() { 
      console.log("doPrint() is printing a string…"); 
   } 
} 
var obj = new StringPrinter(); 
obj.doPrint();

ES6 Class Inheritance Example2

node

'use strict' ;
class Root { 
   test() { 
      console.log("call from parent class") 
   } 
} 
class Child extends Root {} 
class Leaf extends Child {}

//indirectly inherits from Root by virtue of inheritance {} 
var obj = new Leaf();
obj.test() ;

ES6 Class Inheritance

node

'use strict' 
class Shape { 
   constructor(a) { 
      this.Area = a
   } 
} 
class Circle extends Shape { 
   disp() { 
      console.log("Area of the circle:  "+this.Area) 
   } 
} 
var obj = new Circle(223); 
obj.disp()

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