Toggle two CSS classes using jQuery

First create two paragraphs and a button in HTML.

<h3>This is heading</h3>
<p>jQuery is a fast, small and feature-rich <b>JavaScript</b> library.</p>
<p>'Write less: Do more'</p>
<button id="button">Click here to toggle classes</button>

Now create two different classes in CSS.

<style>
.clr1{
	background-color:#CCF;
	color:#60F;
}
.clr2{
	background-color:#FC3;
	color:#360;
}
</style>

Now the jQuery part. Here we want to toggle the classes when button is pressed. Lets see how its done.

$(document).ready(function() {
	$("p").addClass("clr1");	
    $("#button").click(function(){
		$("p").toggleClass("clr1 clr2");		
	});
});

Lets look at the full code.

<style>
.clr1{
	background-color:#CCF;
	color:#60F;
}
.clr2{
	background-color:#FC3;
	color:#360;
}
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<script>
$(document).ready(function() {
	$("p").addClass("clr1");	
    $("#button").click(function(){
		$("p").toggleClass("clr1 clr2");		
	});
});
</script>

<h3>This is heading</h3>
<p>jQuery is a fast, small and feature-rich <b>JavaScript</b> library.</p>
<p>'Write less: Do more'</p>
<button id="button">Click here to toggle classes</button>

That’s it. Now when you press the button paragraph color is changed or toggled between two classes.

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Change the color to red if text exceeds the limit in textarea using jQuery

First we should know that by using maxlength attribute in textarea we can limit the characters without using any additional coding.

Here is the code for maxlength attribute in textarea. Click here for demo.

<textarea rows="4" cols="50" maxlength="15">
Enter text here...</textarea>

For our example lets create a simple textarea with cols=”20” and rows=”5”, give it an id="mytextarea".

<textarea id="mytextarea" cols="20" rows="5"></textarea>

Now the jQuery part, add the jquery library and we will start coding.

$("#mytextarea").keyup(function(){

var maxlength = 15; // specify the maximum length  
 
if($("#mytextarea").val().length > maxlength){
$("#mytextarea").css('color','red');
} 
else{
$("#mytextarea").css('color','black');
}
});

In the above code keyup event occurs whenever key is released. So we are calling anonymous function whenever key is released. We are limiting text in textarea to 15 characters ie maxlength. If text in textarea is greater than 15 ie maxlength, then change text color to red else black. Everything is self explanatory. That’s it.

Let’s look at full code.

<textarea id="mytextarea" cols="20" rows="5"></textarea>

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<script language="JavaScript"><!--  
$("#mytextarea").keyup(function(){
var maxlength = 15; // specify the maximum length  
if($("#mytextarea").val().length > maxlength){
$("#mytextarea").css('color','red');
} 
else{
$("#mytextarea").css('color','black');
}
});
</script>

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Count number of paragraphs inside a div using jQuery

We need to count how many elements present in the page. How do we do this in jQuery?

var count = $("*").length;
alert(count);

In the above code * indicates all elements present on the page and .length is the count of all elements.

Now suppose we have div element with two paragraphs tags and a span tag inside it.

<div id="area">
     <p>Paragraph one</p>
     <p>Paragraph two</p>
     <span></span>
</div>

Now I want to count paragraphs present in the div element. Here we are not bothered about the elements outside the div element but only inside. We can do it like this.

var count = $("#area").find("p").length;
alert(count);

Now the output will be 2.

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Insert data into MYSQL database using jQuery, Ajax, PHP, MYSQL

Create a HTML form with id=”myform”, action=”userinfo.php”, and method=”post”. Add name and age text fields and add name attribute. Create a button, give it id=”sub”. Finally create a span with id=”result” and close it.

<form id="myform" action="userinfo.php" method="post">
Name:<input type="text" name="name"><br>
Age:<input type="text" name="age"><br>
<button id="sub">Save</button>
<span id="result"></span>

Create a new PHP file name it as userinfo.php. Write database connections and select the database. Now get the posted values in variables. Finally execute the MYSQL statement and echo the output.

<?php
//userinfo.php file
//Database connection
$conn = mysql_connect('localhost','root','');
$db = mysql_select_db('test');

//Posted values
$name = $_POST['name'];
$age = $_POST['age'];

if(mysql_query("Insert into user values('$name', '$age')"))
	echo  "Successfully inserted";
else
	echo "Insertion failed";
?>

Now write the jQuery script, first we need to serialize the data taken from input boxes. Then post them using jQuery post method and append the result in span tags.

$("#sub").click(function(){
var data = $("#myform :input").serializeArray();
$.post( $("#myform").attr("action"), data, function(info){
$("#result").html(info);
clearinput();
});
});

In the above code clearinput() is the function we will talk about it later. Now when the form is submitted it should not redirect to PHP page. So we write the following code.

$("#myform").submit(function(){
return false;
});

Now every thing is fine. But the text fields are to be cleared when form is submitted. So we will write a code to clear the text fields. We will write clearinput() function to clear the fields.

function clearinput(){
$("#myform :input").each(function(){
$(this).val('');
});
}

Now let’s see the full code in one place.

<form id="myform" action="userinfo.php" method="post">
Name:<input type="text" name="name"><br>
Age:<input type="text" name="age"><br>
<button id="sub">Save</button>
<span id="result"></span>

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>

<script>
$("#sub").click(function(){
var data = $("#myform :input").serializeArray();
$.post( $("#myform").attr("action"), data, function(info){
$("#result").html(info);
clearinput();
});
});

$("#myform").submit(function(){
return false;
});

function clearinput(){
$("#myform :input").each(function(){
$(this).val('');
});
}
</script>

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Create a textarea with word count using jQuery and PHP

First create a textarea and give it id and name. Add text “Word Count:” and a span tag with id “count” like shown below.

<textarea cols="20" rows="5" name="textarea" id="textarea"></textarea>
<br>Word count: <span id="count"></span>

Now we will write jQuery code so you need to add jQuery library.  We will use the keyup event in the jQuery to call function. So whenever key is released we will call anonymous function to execute the code.

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<script>
$("#textarea").keyup(function(){

});
</script>

Here we are calling a function whenever we type a character in textarea ie., to count number of words typed in the textarea. Now whenever we type character in textarea we need to count number of words present in the textarea.

We have a built-in function in PHP to count the number of words. So now we should send the typed words to the PHP script and get the output. We can do this using jQuery ajax method.

$.ajax({
    url: 'count.php',
    type: "POST",
    data: {textarea:$("#textarea").val()},
    dataType :'html',
    success: function(result){
        $("#count").empty();
        $("#count").append(result);

    },
    error: function(){
        alert("Ahh! something went wrong. Please try again after sometime.");
    }   
});

In the above code we are sending the data typed in the textarea to count.php file. If success append it to span tag else alert a message. Let’s see the count.php file.

<?php
$str = $_POST['textarea'];
$count = str_word_count($str);
echo $count;
?>

Since we are sending values using post method we are using $_POST in php to store the value in variable. str_word_count will count the number of words in variable $str. Finally output is echoed.

Let’s see the final code.

<textarea cols="20" rows="5" name="textarea" id="textarea"></textarea>
<br>Word count: <span id="count"></span>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<script>
$("#textarea").keyup(function(){

$.ajax({
    url: 'count.php',
    type: "POST",
    data: {textarea:$("#textarea").val()},
    dataType :'html',
    success: function(result){
	$("#count").empty();
	$("#count").append(result);
    },
    error: function(){
	alert("Ahh! something went wrong. Please try again after sometime.");
    }   
});
</script>

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Convert comma separated words into an array

Sometimes we want to convert a string into an array. String is comma separated words like adam, adam@yahoo.com, male.

You can do the string to array conversion easily with explode function in PHP.

<?php
$myString = "adam,adam@yahoo.com,male";
$myArray = explode(',', $myString);
print_r($myArray);
?>

Output:

Array
(
    [0] => adam
    [1] => adam@yahoo.com
    [2] => male
)

This way you can convert string into array.

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