THA7

THA DAY 7

1. Write a JavaScript program to list the properties of a JavaScript object. Sample object: var student = { name : "David Rayy", sclass : "VI", rollno : 12 }; 

CODE-
function _keys(obj) 
 {
    if (!isObject(obj)) return [];
    if (Object.keys) return Object.keys(obj);
    var keys = [];
    for (var key in obj) if (_.has(obj, key)) keys.push(key);
    return keys;
  }

2.Write a JavaScript program to delete the rollno property from the following object. Also print the object before or after deleting the property. 

CODE-
var student =  { 
  name : "David Rayy", 
  sclass : "VI", 
  rollno : 12  };
delete student.rollno;
console.log(student);

3. Write a JavaScript program to get the length of a JavaScript object.  Sample object : var student = { name : "David Rayy", sclass : "VI", rollno : 12 }; 

CODE-
Object.objsize = function(Myobj) {
    var size = 0, key;
    for (key in Myobj) {
        if (Myobj.hasOwnProperty(key)) size++;
    }
    return size;
};




4. Write a JavaScript program to display the reading status (i.e. display book name, author name and reading status) of the following books. 
var library = [ { author: 'Bill Gates', title: 'The Road Ahead', readingStatus: true }, 
{ author: 'Steve Jobs', title: 'Walter Isaacson', readingStatus: true },
{ author: 'Suzanne Collins', title: 'Mockingjay: The Final Book of The Hunger Games', readingStatus: false }]; 

CODE-
for (var i = 0; i < library.length; i++) 
   {
    if (library[i].readingStatus) {
      console.log("read");
    } else
    {
     console.log("not read");
    }
   }
   
   
5. Write a JavaScript program to get the volume of a Cylinder with four decimal places using object classes. 
Volume of a cylinder : V = πr2h where r is the radius and h is the height of the cylinder. 

CODE-
function Cylinder(cyl_height, cyl_diameter) {
  this.cyl_height = cyl_height;
  this.cyl_diameter = cyl_diameter;
}

Cylinder.prototype.Volume = function () {
  var radius = this.cyl_diameter / 2;
  return this.cyl_height * Math.PI * radius * radius;
};

var cyl = new Cylinder(7, 4);
console.log('volume =', cyl.Volume().toFixed(4));


6. Write a JavaScript program to sort an array of JavaScript objects.