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Inserting comments in a computer code is supposed to be a good programming practice. Comments are helpful for understanding the logic of the program. They also serve as a documentation. You can put comments in a HTML as well as XML script, just as in a program written in C, Java, Python etc. BeautifulSoup API can be helpful to identify all the comments in a HTML document.
In HTML and XML, the comment text is written between <!– and –> tags.
<!-- Comment Text -->
The BeutifulSoup package, whose internal name is bs4, defines Comment as an important object. The Comment object is a special type of NavigableString object. Hence, the string property of any Tag that is found between <!– and –> is recognized as a Comment.
Example
from bs4 import BeautifulSoup markup = "<b><!--This is a comment text in HTML--></b>" soup = BeautifulSoup(markup, ''html.parser'') comment = soup.b.string print (comment, type(comment))
Output
This is a comment text in HTML <class ''bs4.element.Comment''>
To search for all the occurrences of comment in a HTML document, we shall use find_all() method. Without any argument, find_all() returns all the elements in the parsed HTML document. You can pass a keyword argument ”string” to find_all() method. We shall assign the return value of a function iscomment() to it.
comments = soup.find_all(string=iscomment)
The iscomment() function verifies if the text in a tag is a comment object or not, with the help of isinstance() function.
def iscomment(elem): return isinstance(elem, Comment)
The comments variable shall store all the comment text occurrences in the given HTML document. We shall use the following index.html file in the example code −
<html>
<head>
<!-- Title of document -->
<title>TutorialsPoint</title>
</head>
<body>
<!-- Page heading -->
<h2>Departmentwise Employees</h2>
<!-- top level list-->
<ul id="dept">
<li>Accounts</li>
<ul id=''acc''>
<!-- first inner list -->
<li>Anand</li>
<li>Mahesh</li>
</ul>
<li>HR</li>
<ul id="HR">
<!-- second inner list -->
<li>Rani</li>
<li>Ankita</li>
</ul>
</ul>
</body>
</html>
The following Python program scrapes the above HTML document, and finds all the comments in it.
Example
from bs4 import BeautifulSoup, Comment
fp = open(''index.html'')
soup = BeautifulSoup(fp, ''html.parser'')
def iscomment(elem):
return isinstance(elem, Comment)
comments = soup.find_all(string=iscomment)
print (comments)
Output
['' Title of document '', '' Page heading '', '' top level list'', '' first inner list '', '' second inner list '']
The above output shows a list of all comments. We can also use a for loop over the collection of comments.
Example
i=0 for comment in comments: i+=1 print (i,".",comment)
Output
1 . Title of document 2 . Page heading 3 . top level list 4 . first inner list 5 . second inner list
In this chapter, we learned how to extract all the comment strings in a HTML document.
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