Page 224 - Web Applications (803) Class 12
P. 224

Example:

                     var teacher = {
                       name: "Rahul",                                               //Property
                       age : 45,
                       displayHello: function() {                             //Method
                             document.write ("Welcome");
                       }
                     }
                  3.  List the two advantages and disadvantages of JavaScript.
               Ans.  Advantages:
                      Simple: JavaScript is easy to understand and learn.
                      Speed: As JavaScript is an "interpreted" language, it is faster than other programming languages like Java
                       at  compiling code.  It  speeds up  program  execution  by  removing the  need  for  server  connections  to  be
                       established.

                    Disadvantages:
                      Cannot Debug: While certain HTML editors permit debugging, their efficiency is inferior to that of C or C++
                       editors. Additionally, because the browser doesn't provide any errors, the developer has trouble identifying the
                       problem.

                      Customer-side  Security: The  JavaScript  code  is visible to  all and  can  be  abused by  some people.  These
                       operations can entail making anonymous use of the source code.
                  4.  What do you understand by datatype? What are the different datatypes present in JavaScript?
               Ans.  In programming, a datatype is a categorization that describes the kind of value a variable can hold and the kinds
                    of mathematical, relational, or logical operations that can be performed on it without producing an error. There
                    are 2 types of datatypes in JavaScript:

                      Primitive datatype
                      Non Primitive datatype
                     Primitive datatypes include string, number and Boolean.

                     Non Primitive datatypes include objects and arrays.
                  5.  What is an object? Explain 2 ways of declaring an object.
               Ans.  Consider an object in JavaScript as a list of items, each of which is a property or method that is kept as a key-value
                    pair in memory.

                     You can define and create your own objects in any of the following ways:
                      Using an object literal.

                        The following example creates a new JavaScript object with three properties:
                            const student = {Name : "Rashi", age : 35, Address  : "Ajmer" };
                      Using the keyword new.
                        The following example creates a new JavaScript object using new Object(), and then adds 3 properties:


                        const student = new Object();
                        student.Name = "Rashi";



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