JS & jQuery

1. How many type of Objects and Types in Java Script?

There are 4 types of Object as below.

Intrinsic objects   - Date ,String .number,.....
Host Objects - Window ,document
Creating Objects -  var obj =new Object();
Activex Object


The type of all objects created with a custom constructor is object. There are only six types in JavaScript:
object, function, string, number, boolean, and undefined.

2. How will you send a model from jQuery to C# model?

   $("#updateUserPreference").click(function () {

        var userLocale = $("#ddlUserLocale").val();

        var userTimeZone = $("#ddlUserTimeZone").val();

       

       var  userPreferenceModel = {

            LocaleCode: userLocale,

            TimeZoneId: userTimeZone

       };

       var Id = $("#userId").val();

        $.ajax({

            type: 'POST',

            contentType: 'application/json; charset=utf-8',  // not datatype:json

            url: updateUserPreferences,

            cache: false,

            data:

                JSON.stringify({

                    userPreferenceModel:userPreferenceModel,

                    userId: Id,

                    localeCode: $("#ddlUserLocale").val()

            }),

            success: function (response) {

                var objectData = vkbeautify.json(response);

                $("#output").html(objectData);

                if (successFx) {

                    successFx(response);

                }

            },

            error: function (jqXHR, textStatus) {

                $("#session-error").html("Request failed: " + textStatus).show();

                $("#output").html("Failed.");

            }

        });

    });

3. What is Object and in how many ways can you create object?

In JavaScript, almost "everything" is an object.

• Booleans can be objects (or primitive data treated as objects)
• Numbers can be objects (or primitive data treated as objects)
• Strings can be objects (or primitive data treated as objects)
• Dates are always objects
• Maths are always objects
• Regular expressions are always objects
• Arrays are always objects
• Functions are always objects
• Objects are objects

There are many ways to create objects.

var book = {
    price: somePrice * discount,
    pages: 500,
    pricePerPage: this.price / this.pages
};

using new keyword.

var person = new Object();
person.firstName = "John";
person.lastName = "Doe";
person.age = 50;

using an Object Constructor

function person(first, last, age, eye) {
    this.firstName = first;
    this.lastName = last;
    this.age = age;
    this.eyeColor = eye;
}
var myFather = new person("John", "Doe", 50, "blue");

In Java Script Objects are mutable: They are addressed by reference, not by value.

JavaScript variables are not mutable. Only JavaScript objects.

4. Regex to valid an Email Address.

<input id="forwardMailTo" style="width: 80%;"/>

            <span class="field-validation-error field-validation-valid" id="forwardMailToError" style="margin-left:12%;">EmailErrorMsg</span>

var emailRegex = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/;

    $('#btnSend').click(function () {

        if (emailRegex.test($("#forwardMailTo").val())) {

            ResendOrForwardEmail(true);

            if (!$("#forwardMailToError").hasClass("field-validation-valid")) {

                $("#forwardMailToError").addClass("field-validation-valid");

            }

        }

        else {

            $("#forwardMailToError").removeClass("field-validation-valid");

        }

    });

5. what is dataType and contentType in jquery Ajax calls

• contentType is the header sent to the server, specifying a particular format.
  • Example: I'm sending json or XML
• dataType is you telling jQuery what kind of response to expect.
  • Expecting JSON, or XML, or HTML, etc....the default it for jQuery to try and figure it out.

dataType and contentType

6. Prototypes in JS

7. what is Closures

8. Let vs Var

Toptal Interview-questions