Skip navigation


It is common in forms, to get user inputs for numerical calculations later like house rent allowance for salary calculation. In such scenarios, the value returned is string which if we add result in concatenation. To avoid this mistake adding toInt method to string object directly will be handy.

/**
 * adding toInt method to String object
 * author rajakvk <rajakvk at gmail dot com>
 */
if(!String.toInt) {
  /**
   * Returns integer value if a string value is passed.
   * @name toInt
   * @methodOf String
   * @param {*} none 
   * @returns {Number}
   */
  String.prototype.toInt = function() {
     return parseInt(this, 10);
  }
}
// Usage
// $('#hra').val().toInt();
// typeof $('#hra').val();  // string
// typeof $('#hra').val().toInt();  // number

Note: This method converts string to Integer discarding decimal places.


typeof method in JavaScript returns wrong value if you pass an array as parameter. To fix this, we can add isArray method to JavaScript’s native Array object. In future, if browser includes one such method, the below code will not break as it will use browser’s native code in that case.

This will be handy fix for typeof known bug for Arrays.

/**
 * @author rajakvk <rajakvk(at)gmail.com>
 */
if (!Array.isArray) {
    
    /**
     * Returns true if an object is an array, false if it is not.
     * @name isArray
     * @methodOf Array
     * @param {*} value 
     * @returns {Boolean}
     */
    Array.isArray  = function (value) {
                
        return Object.prototype.toString.call(value) === '[object Array]';
        
    };

}


1) Consider the code:
var someFunc = function() {
var a;
this.b;
c;
}

What are the scopes of variables a, b and c respectively?

Pick one of the choices
a) Private, Public, Global
b) Public, Static, Private
c) Global, Public, Static
d) Static, Public, Global

****************

2) Which of the following is NOT a benefit of using anonymous functions?

Pick one of the choices
a) The global space remains unpolluted
b) Anonymous functions can be self executing
c) Anonymous functions can be used to pass self references
d) Anonymous functions can be passed as callbacks

*********************

3) Inside a javascript function, which of the following will return a reference to the function itself?

Pick one of the choices
a) arguments
b) arguments.callee
c) arguments.callee.caller
d) this

*******************

4) Inside a javascript function, which of the following will return a reference to the calling function?

Pick one of the choices
a) this.caller
b) arguments.caller
c) this.callee.caller
d) arguments.callee.caller

***************

5) Which of the following is true about null ?

Pick one of the choices
a) It can implicitly be assigned by the JS environment to a variable
b) It is the same as undefined since null==undefined returns true
c) It is truthy in nature
d) The type of null is object

*************

6) Which of these is not a falsy value?

Pick one of the choices
a) “” (empty string)
b) [] (empty array)
c) null
d) undefined

**************

7) Consider the code :

var func = (function() {
var a = ‘Hello World’;
var b = function() {
return a;
}
return b;
})() ;

This is an example of ?

Pick one of the choices
a) Method Overloading
b) Closure
c) Closure and Anonymous Functions
d) Closure, Anonymous Functions and Self Executing Functions

***************

8) Consider the following statements:

a) An inner function has access to the variables of its parent function
b) A parent function has access to the variables of its inner functions
c) Variables declared inside a function are accessible outside of it as well
d) Variables declared outside any functions are accessible globally

Which of the above statements are true?

Pick one of the choices
a) I only
b) II only
c) I and III only
d) I and IV only

********************

9) When an object is assigned to a variable using the assignment (=) operator, what really happens?

Pick one of the choices
a) The object is copied to the new variable
b) The object’s reference is copied to the new variable
c) There is a compile error since objects cannot be copied
d) There is a run time error since objects cannot be copied

********************

10) The prototype is :

Pick one of the choices
a) A property of each object
b) A property of each function
c) A method of each object
d) A method of each function

****************

11) For any given function func , func.prototype.constructor will return?

Pick one of the choices
a) A reference to the function itself
b) A reference to the calling function
c) The function will call itself
d) A reference to the prototype object

*****************

12) For any given object obj, obj.constructor.prototype will return?

Pick one of the choices
a) Undefined
b) Error because o.constructor is not defined
c) The prototype of the object’s constructor function
d) The object’s constructor function

*******************

13) The type of prototype is?

Pick one of the choices
a) Function
b) String
c) Object
d) Array

*******************

14) To replicate an object exactly, you need to:

Pick one of the choices
a) Assign the object to a new variable
b) Extend the object with shallow copy
c) Extend the object with deep copy
d) Objects cannot be replicated. Only their references can be reassigned

*******************

15) Consider the code:

function foo() {
“use strict”;
// … your code …
}

This will:

Pick one of the choices
a) Throw a compile error as a string literal has been left unassigned
b) Will ignore the unassigned string literal and move on
c) Throw a warning stating that an unassigned string literal was found
d) Start throwing errors for potentially unsafe actions inside the function

Follow

Get every new post delivered to your Inbox.

Join 216 other followers