JQuery: Synchronize two ASP.Net text boxes


jquery1

“The central concept behind jQuery is – find something, do something. More specifically, select DOM element(s) from an HTML document and then do something with them using jQuery methods. This is the big picture concept.” ___________________________Cody Lindley(jQuery Succinctly)

Introduction:

As the title suggests, this post is about interacting with two ASP.Net text boxes. If any change/interaction happens to one of the text boxes then we’ll try to do the same to the other text box, programmatically.

Live Demo & Code

Live demo here
Download code hereDownload

Designing the UI:

Let’s start with a new WebForm. The UI in this case requires only two multiline text boxes separated by some white spaces. To keep things simple we’ll concentrate on ‘how it works’ rather than ‘how it looks’. Now, the above quotation indicates that we need to find something and do something and thus it is a two step process. Here the ‘something’ is the text boxes and we can find them by their ids, class, tag, type etc. Particularly for this example we’ll employ the find by class trick. So, we need to mention same CssClass for both the text boxes and thing to notice is- this class may not exists at all.

<div>
     <asp:TextBox runat="server" ID="TextBox1" CssClass="sync" TextMode="MultiLine" Height="100px" />&amp;nbsp;&amp;nbsp;
     <asp:TextBox runat="server" ID="TextBox2" CssClass="sync" TextMode="MultiLine" Height="100px" />
</div>

Writing the Code:

In the script part, we’ll code for two things-

  • Synchronizing the text typed in to one text box with the other
  • Synchronizing the scrolling in both the text boxes

So, we will write two functions for these two specific actions. The first operation can be done on keyup event and the second with scroll event.

<script>
        $(document).ready(function () {
            $(".sync").keyup(function () {
                $(".sync").val($(this).val());
            });
            $(".sync").scroll(function () {
                $(".sync").scrollTop($(this).scrollTop());
            });
        });
</script>

Result:

As I already have said, we can demonstrate two operations

  • Typing anything in to one of the text box will result in displaying same text in the other text box, simultaneously.
  • Type few lines of code so that the scroll bar is visible. Now when we scroll any of the text boxes using either keyboard or mouse, other one will be scrolled automatically.

Explaination:

We have embedded our code inside $(document).ready() function as this function is executed after the DOM is loaded and before the page contents are rendered in to the browser. We can define a common function for both the textboxes with the use of CssClass name. The first action is defined inside the keyup event so that when we release the key the action will be performed. The action here is nothing but copying the content of the current text box to the other. The val() with no argument returns the value of the text box and when some argument is passed to it, sets the argument as value of that text box. I hope this made the thing very clear and further explanation is not required. Now consider about the second action. The scroll() event is fired when we try to scroll the content of text box either through key board or mouse. Again, scrollTop() with zero argument returns the current scroll position but, sets the scroll positions to a value same as the argument if called with an argument.

Conclusion:

Now we are able to develop a page with two text boxes which are synchronized upon typing text in to them or using the scroll bar. We can use more than two text boxes and it will still work as long as we use a common CssClass for them.

I hope you have enjoyed reading this post. Your feedback is very important to me.

JQuery: Consuming Page Method in ASP.Net


jquery1

Introduction: Page Method is an easy way to communicate with the code behind and JQuery functions for simple operations. Although it can be done using web services or WCF but, for simple operations there is no need to complicate things. This post is a simple demo of how we can consume page methods in ASP.Net using AJAX. Note: This example produces summation of two inputted integers as result and I know in real life this logic is not going to help you but, as I already said my intention is to show only a way to consume page methods with JQuey using AJAX so, you can definitely replace your logic here.

Demo:
1. Place two Textbox(ID: txtNum1, txtNum2) and a Button (ID: btnSum) in the page.

<div>Enter two integers and click <strong>SUM</strong> button to get the result
<div style="padding: 5px;">First Number</div>
<div style="padding: 5px;">Second Number</div>
</div>

2. Create a page method (SumIntegers()) in code behind with two integer parameters named num1 and num2. Don’t forget to assign [WebMethod()] attribute to it for which you need to add namespace System.Web.Services and to call the page method directly make it static.

using System;
using System.Web.Services;

public partial class WebMethodDemo : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e){}

    [WebMethod()]
    public static int SumIntegers(int num1, int num2)
    {
        return num1 + num2;
    }
}

3. Now the last thing to do is to write the JQuery section where we will be able to call the ajax method to get the desired result.

<script type="text/javascript">// <![CDATA[
        $(document).ready(function () {
            $("#btnSum").click(function (e) {

                var num1 = $("#txtNum1").val();
                var num2 = $("#txtNum2").val();
                $.ajax({
                    type: "POST",
                    url: window.location.href + "/SumIntegers",
                    data: '{"num1":"' + num1 + '","num2":"' + num2 + '"}',
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    success: function (msg) {
                        alert(num1+"+"+num2+"="+msg.d);
                    },
                    error: function () {
                        alert("Error occured. Please check inputs !");
                    }
                });
            });
        });

// ]]></script>

Explanation: As you may know, $(document).ready() function gets executed as soon as DOM is loaded and before the page contents are rendered in to the browser. We need to embed all the JQuery markup inside this function. Define an event handler for click event of button ‘btnSum’. Rest of the logic is written inside this event handler as we want to execute our logic on clicking the button. First retrieve the values from the textboxes. Now to perform the asynchronous HTTP(ajax) request, call the .ajax() method of JQuery with the url and necessary settings. If the ajax call succeeds then we can get the returned result using msg.d as the result will always be enclosed within the ‘d’ (since ASP.Net 3.5, which prevents direct execution of the string as script).

Downloads: Demo Project Download

I hope this is useful.

Thanks for reading and please don’t forget to add a comment.

Book: Visual Studio 2012 and .NET 4.5 Expert Development Cookbook


book
Book Title
: Visual Studio 2012 and .Net 4.5 Expert Development Cookbook
Author: Abhishek Sur (www.abhisheksur.com)
About Author: Abhishek Sur is a Microsoft MVP in Client App Dev since 2011. He is an architect in the .NET platform.  He is also a renowned public speaker and owns one of the most active  Microsoft user group named Kolkata Geeks.  His website abhisheksur.com guides both budding and experienced developers to understand the details of languages and latest technology. You may also follow him at Facebook or Twitter .

The very first thing I like about this book is its conciseness. Even though it is a 380 pages book you will find every aspect of the enhancement & new features introduced with Visual Studio 2012 and .Net 4.5 has been  explained extensively with proper examples. Starting with the Visual Studio IDE features, author marches us through the enhancement to ASP.Net, WPF etc. It has a dedicated chapter on memory management too.


I always go for the shortcuts while developing applications and also love to use features provided by my IDE for faster development. This book is a good educator of  IDE features and shortcuts introduced in Visual Studio 2012 which will help you in saving development time.
The key component of the book is, everything comes with a proper example. With this book, one can also learn –

  • In-depth memory management helps to to grasp under the hood happenings.
  • Asynchronous programming has become very important in the last few years and the book explains all about the necessity and usage of Asynchronous Programming in .Net
  • Enhancement to ASP.Net includes support for HTML5, Web Socket, JQuery and been explained beautifully.
  • Enhancement to WPF
  • Building Windows 8 style applications and communication & sharing between apps and devices.

In case you want to check it out before buy, you can download Chapter-1: Introduction to Visual Studio IDE features for free.

You can buy it from packtpub.com or amazon.com

Honestly speaking, I have been immensely benefited from C# internal series by the author on his blog DOT NET TRICKS and this book further helped me to discover the roots.
It is not conclusive by any means and there is a much more to grab. At last, if you are a .Net developer and a technology loving person then you’ll definitely love to add this book to your bookshelf.

HTML: Design table with thin single line border


SingleLineBorder_2

In this quick tips, we will see a way to render an HTML table with single line(thin) border.

Generally when we write mark-up for HTML table with border specified, it renders as Fig. A which looks ugly with a very thick border. In Fig. A I have used markup starting with following line

 
<table border="1" cellpadding="0" cellspacing="0" width="200px">

Figure A & Figure B

Now, to have the HTML table to be rendered as Fig. B with thin border, we need to add style attribute with css property border-collapse set to collapse.

<table border="1" cellpadding="0" cellspacing="0" width="200px" style="border-collapse:collapse;">

I hope, it’s useful.

ASP.Net: Disable TabIndex Focusing


If you need to disable/restrict focusing on one or more controls in a page then just mention TabIndex=”-1″.

This is useful particularly when you have some read only controls in your WebForm and you don’t want the control to move(focus) to those controls.

This is known to most of the web-developers but hopefully it will be useful to others.

Javascript: Thousand separator


We may use following javascript function to show numbers formatted with thousands separator.

Definition

function formatThousandPlace(orgNum) {
    arr = orgNum.split('.');    //split integer part &amp; fractional part
    intPart = arr[0];           //store integer part in a variable
    fractionPart = arr.length > 1 ? '.' + arr[1] : '';  //store fractional part in a variable
    var rgx = /(\d+)(\d{3})/;   //regexp to find thousand place
            
    while (rgx.test(intPart)) { 
        intPart = intPart.replace(rgx, '$1' + ',' + '$2');  //replace integer part after inserting a comma in the thousandth place
    }
    
    document.write(intPart + fractionPart); //write final value to the document
}

Function Call
Now, we can use it anywhere in the document where we want to show those numbers. For example: it may inside normal html elements or some dynamic ASP.Net controls like GridView, DataList, FormView etc.

<script language="javascript">formatThousandPlace('10000000.00')</script>

While calling this from ItemTemplate of an ASP GridView the syntax will be

<asp:TemplateField HeaderText="Price">
    <ItemTemplate>
       <script language="javascript">formatThousandPlace('<%#Eval("SalePrice") %>')</script>
    </ItemTemplate>
</asp:TemplateField>

I hope this is helpful.

C Sharp: Under-utilized Padleft() method


What I am going to explain is not for a specific situation, we can use it in so many cases. I am talking about PadLeft() method of string class. To explain it, I am just showing you an example, which I found somebody doing while he is supposed to code for three dropdowns like Day,Month & Year. Following is the snippet of his code-

private void bindDay()
    {        
        ArrayList day = new ArrayList();
        for (var i = 1; i <= 31; i++)
        {
            if (i > 0 && i < 10)
            {
                var x = "0" + i;
                day.Add(x);
            }
            else
                day.Add(i);
        }
        ddlDays.DataSource = day;        
        ddlDays.DataBind();
}

Although this block of snippet may need improvements on some other line(s) of code but I am concentrating on the part inside the ‘for loop’. Yes, the if .. else .. block. Here, 5-7 lines of the code is intended to add days of date and with 2-digit format like 01,02,03..etc. I admit that there are so many ways to accomplish it, but I am just talking about the logic. In this code, it has a loop variable which checks the value to find if it is of single digit or two digits. Then if it is of 2-digits then no logic to go before adding it to the dropdownlist and if it is of 1-digit then it is to be padded with a ‘0’..This will work definitely fine for Day dropdown.

Now we can ask what happen when some body wants to form a dropdown with fixed no of 10 digits and a dumb answer will be -“Use 9-10 if..else conditions to do this”.

We can replace the whole if .. else .. by just using a simple method of System.String class – PadLeft(). Now after changing only the if else block with PadLeft(), the code will be like-

private void bindDay()
    {        
        ArrayList day = new ArrayList();
        for (var i = 1; i <= 31; i++)
        {
               day.Add(i.ToString().PadLeft(2,'0'));
        }
        ddlDays.DataSource = day;        
        ddlDays.DataBind();
} 

Here , PadLeft() is taking 2 parameters- width of the resulted string and the character to be padded to the left when string is of length less than 2.
This can also be used to scenarios where you need to generate a code (like Employee Code,Book Code, etc) of a fixed length.