HTML 10 - Comments

emanlee發表於2024-05-18
HTML

HTML Comments are used to comment in HTML codes, so the developer can understand the purpose of that code section and it is helpfull for debugging also. If we are facing some issue becouse of any particular element we cah check it by commenting out that element.

What are HTML Comments?

HTML comment tag is used to create a comment. A comment in HTML is like a note for yourself and others. Comments are completely ignored by web browsers, so they don't affect how your page looks or works. There are two types of comment in HTML.

  • Single Line Comment: The single-line comment is given inside the <!-- ... -->.
  • Multi Line Comment: Same as single-line comment but if we add multiple lines in the comment we will have multi-line comments.

Why to use HTML Comments?

Comments help you and others to understand the code and increases code readability. HTML comments are placed in between <!-- ... --> tags. So, any content placed with-in <!-- ... --> tags will be treated as comment and will be completely ignored by the browser.

Examples of HTML Comments

In the bellow examples we will witness single and multiline both types of comments.

HTML Single Line Comment

Here in this example we will use single line comment for each element used in the body tag.

<!DOCTYPE html>
<html>
<head>
    <title>Online HTML Editor</title>
</head>
<body>
    <!-- This is a single Comment-->
    <h1>Tutorialspoint</h1>
    <!-- This is a single line Commnet -->
    <p>Simply Easy Learning</p>
</body>
</html>

HTML Multi Line Comment

Here in this example we will use multi line comment for each element used in the body tag.

<!DOCTYPE html>
<html>
<head>
    <title>Online HTML Editor</title>
</head>
<body>
    <!-- 
       This is a multiline Comment
       Heading Section
    -->
    <h1>Tutorialspoint</h1>
    <!-- 
       This is a multiline line Commnet 
       paragrapgh Scetion 
    -->
    <p>Simply Easy Learning</p>
</body>
</html>

Note: We can not use the above approach of commenting on internal CSS and JavaScript section. In the <style> and <script> tag we have to use CSS and JavaScript comment syntax.

Hide Content using HTML Comment

This is required when we will work on debugging HTML code, this will help us to not to render specific html element.

<!DOCTYPE html>
<html>
<head>
    <title>Hiding p Element</title>
</head>
<body>
    <h1>Tutorialspoint</h1>
    <!--  <p>Simply Easy Learning</p> -->
</body>
</html>

Valid vs Invalid Comments

Comments in HTML have a single that you need to follow. You need make sure that there are no spaces in the start or end of comment string.

<!DOCTYPE html>
<html>
<head>
   <title>Valid & Invalid Comment</title>
</head>
<body>
   <!--   This is valid comment -->
   < !--   This is not a valid comment -->
   < !--   This is not a valid comment -- >
</body>
</html>

Conditional Comments

Conditional comments are a feature specific to Internet Explorer (IE) on Windows but they are ignored by other browsers. They are supported from Explorer 5 onwards, and you can use them to give conditional instructions to different versions of IE.

<!DOCTYPE html>
<html>
<head>
   <title>Conditional Comments</title>
   <!--[if IE 6]>
      Special instructions for IE 6 here
   <![endif]-->
</head>
<body>
   <p>Document content goes here.....</p>
</body>
</html>

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