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JQUERY - ID SELECTORS


To understand ID Selectors, let us take the below example, where we have three <p> tags.


Example :



<html>
    <head>
    	<title> My First Programme </title>
  	</head>

  	<body>
    	<h1> JQuery </h1>
    	<p id = "para1"> First Paragraph </p>
    	<p id = "para2"> Second Paragraph </p>
    	<p id = "para3"> Third Paragraph </p>
  	</body>
</html>



Now since, in the above code, there are three <p> tags,


<p id = "para1"> First Paragraph </p>
<p id = "para2"> Second Paragraph </p>
<p id = "para3"> Third Paragraph </p>

We have used the CSS ID attributes for each <p> tags. So that we can differentiate between the three <p> tags.


Note : To understand 'ID Selectors', a little understanding of CSS ID is needed.

Now, let us say, we want to change the contents of the first <p> tag,


<p id = "para1"> First Paragraph </p>

From First Paragraph to My New First Paragraph using JQuery.


Now since, there are three <p> tags, we need to specify the ID Selectors to make use of the CSS ID name i.e. para1.


<p id = "para1"> First Paragraph </p>

So, let us rewrite the above code using ID Selectors of JQuery.


Example :



<html>
    <head>
    	<title> My First Programme </title>
  	</head>

  	<body>
    	<h1> JQuery </h1>
    	<p id = "para1"> First Paragraph </p>
		<p id = "para2"> Second Paragraph </p>
		<p id = "para3"> Third Paragraph </p>
			
    	<script src = "https://cdnjs.cloudflare.com/ajax/libs/JQUERY/3.3.1/jquery.min.js"> </script>
	  
      	<script>
      
			$('#para1').text("My New First Paragraph");
            
      	</script>    
   </body>
</html>


Output :



So, if you see the above output. We can see that the content of the first <p> tag,


<p id = "para1"> First Paragraph </p>

Got changed to My New First Paragraph.


And this happened with the one liner code of JQuery.


<script>
	$('#para1').text("My New First Paragraph");
</script>

In the JQuery code we have located the <p> element and specified the ID name followed by .' i.e. #para1.

java_Collections

Just remember, in the ID selector, the ID name should start with a hash # i.e. #para1.


$('#para1').text("My New First Paragraph");

So, when JQuery finds that a selector that starts with a hash # (i.e. #para1), it assumes that we ar searching for a CSS ID.


And finds that there are three elements with ID attribute.


<p id = "para1"> First Paragraph </p>
<p id = "para2"> Second Paragraph </p>
<p id = "para3"> Third Paragraph </p>

And the first attribute,


<p id = "para1"> First Paragraph </p>

Matches with the ID name para1. And changes its content with My New First Paragraph.