Is there an easy way to take a string of html in JavaScript and strip out the html?
If you're running in a browser, then the easiest way is just to let the browser do it for you...
function stripHtml(html)
{
let tmp = document.createElement("DIV");
tmp.innerHTML = html;
return tmp.textContent || tmp.innerText || "";
}
Note: as folks have noted in the comments, this is best avoided if you don't control the source of the HTML (for example, don't run this on anything that could've come from user input). For those scenarios, you can still let the browser do the work for you - see Saba's answer on using the now widely-available DOMParser.
myString.replace(/<[^>]*>?/gm, '');
<img src=http://www.google.com.kh/images/srpr/nav_logo27.png onload="alert(42)"
if you're injecting via document.write
or concatenating with a string that contains a >
before injecting via innerHTML
.
>
will be left in the second. That's not an injection hazard though. The hazard occurs due to <
left in the first, which causes the HTML parser to be in a context other than data state when the second starts. Note there is no transition from data state on >
.
<button onClick="dostuff('>');"></button>
Assuming correctly written HTML, you still need to take into account that a greater than sign might be somewhere in the quoted text in an attribute. Also you would want to remove all the text inside of <script>
tags, at least.
Simplest way:
jQuery(html).text();
That retrieves all the text from a string of html.
I would like to share an edited version of the Shog9's approved answer.
As Mike Samuel pointed with a comment, that function can execute inline javascript codes. But Shog9 is right when saying "let the browser do it for you..."
so.. here my edited version, using DOMParser:
function strip(html){
let doc = new DOMParser().parseFromString(html, 'text/html');
return doc.body.textContent || "";
}
here the code to test the inline javascript:
strip("<img onerror='alert(\"could run arbitrary JS here\")' src=bogus>")
Also, it does not request resources on parse (like images)
strip("Just text <img src='https://assets.rbl.ms/4155638/980x.jpg'>")
As an extension to the jQuery method, if your string might not contain HTML (eg if you are trying to remove HTML from a form field)
jQuery(html).text();
will return an empty string if there is no HTML
Use:
jQuery('<p>' + html + '</p>').text();
instead.
Update: As has been pointed out in the comments, in some circumstances this solution will execute javascript contained within html
if the value of html
could be influenced by an attacker, use a different solution.
$("<p>").html(html).text();
jQuery('<span>Text :) <img src="a" onerror="alert(1)"></span>').text()
Converting HTML for Plain Text emailing keeping hyperlinks (a href) intact
The above function posted by hypoxide works fine, but I was after something that would basically convert HTML created in a Web RichText editor (for example FCKEditor) and clear out all HTML but leave all the Links due the fact that I wanted both the HTML and the plain text version to aid creating the correct parts to an STMP email (both HTML and plain text).
After a long time of searching Google myself and my collegues came up with this using the regex engine in Javascript:
str='this string has <i>html</i> code i want to <b>remove</b><br>Link Number 1 -><a href="http://www.bbc.co.uk">BBC</a> Link Number 1<br><p>Now back to normal text and stuff</p>
';
str=str.replace(/<br>/gi, "\n");
str=str.replace(/<p.*>/gi, "\n");
str=str.replace(/<a.*href="(.*?)".*>(.*?)<\/a>/gi, " $2 (Link->$1) ");
str=str.replace(/<(?:.|\s)*?>/g, "");
the str
variable starts out like this:
this string has <i>html</i> code i want to <b>remove</b><br>Link Number 1 -><a href="http://www.bbc.co.uk">BBC</a> Link Number 1<br><p>Now back to normal text and stuff</p>
and then after the code has run it looks like this:-
this string has html code i want to remove
Link Number 1 -> BBC (Link->http://www.bbc.co.uk) Link Number 1
Now back to normal text and stuff
As you can see the all the HTML has been removed and the Link have been persevered with the hyperlinked text is still intact. Also I have replaced the <p>
and <br>
tags with \n
(newline char) so that some sort of visual formatting has been retained.
To change the link format (eg. BBC (Link->http://www.bbc.co.uk)
) just edit the $2 (Link->$1)
, where $1
is the href URL/URI and the $2
is the hyperlinked text. With the links directly in body of the plain text most SMTP Mail Clients convert these so the user has the ability to click on them.
Hope you find this useful.
An improvement to the accepted answer.
function strip(html)
{
var tmp = document.implementation.createHTMLDocument("New").body;
tmp.innerHTML = html;
return tmp.textContent || tmp.innerText || "";
}
This way something running like this will do no harm:
strip("<img onerror='alert(\"could run arbitrary JS here\")' src=bogus>")
Firefox, Chromium and Explorer 9+ are safe. Opera Presto is still vulnerable. Also images mentioned in the strings are not downloaded in Chromium and Firefox saving http requests.
<script><script>alert();
This should do the work on any Javascript environment (NodeJS included).
const text = `
<html lang="en">
<head>
<style type="text/css">*{color:red}</style>
<script>alert('hello')</script>
</head>
<body><b>This is some text</b><br/><body>
</html>`;
// Remove style tags and content
text.replace(/<style[^>]*>.*<\/style>/gm, '')
// Remove script tags and content
.replace(/<script[^>]*>.*<\/script>/gm, '')
// Remove all opening, closing and orphan HTML tags
.replace(/<[^>]+>/gm, '')
// Remove leading spaces and repeated CR/LF
.replace(/([\r\n]+ +)+/gm, '');
<html><style..>* {font-family:comic-sans;}</style>Some Text</html>
I altered Jibberboy2000's answer to include several <BR />
tag formats, remove everything inside <SCRIPT>
and <STYLE>
tags, format the resulting HTML by removing multiple line breaks and spaces and convert some HTML-encoded code into normal. After some testing it appears that you can convert most of full web pages into simple text where page title and content are retained.
In the simple example,
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<!--comment-->
<head>
<title>This is my title</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style>
body {margin-top: 15px;}
a { color: #D80C1F; font-weight:bold; text-decoration:none; }
</style>
</head>
<body>
<center>
This string has <i>html</i> code i want to <b>remove</b><br>
In this line <a href="http://www.bbc.co.uk">BBC</a> with link is mentioned.<br/>Now back to "normal text" and stuff using <html encoding>
</center>
</body>
</html>
becomes
This is my title This string has html code i want to remove In this line BBC (http://www.bbc.co.uk) with link is mentioned. Now back to "normal text" and stuff using
The JavaScript function and test page look this:
function convertHtmlToText() {
var inputText = document.getElementById("input").value;
var returnText = "" + inputText;
//-- remove BR tags and replace them with line break
returnText=returnText.replace(/<br>/gi, "\n");
returnText=returnText.replace(/<br\s\/>/gi, "\n");
returnText=returnText.replace(/<br\/>/gi, "\n");
//-- remove P and A tags but preserve what's inside of them
returnText=returnText.replace(/<p.*>/gi, "\n");
returnText=returnText.replace(/<a.*href="(.*?)".*>(.*?)<\/a>/gi, " $2 ($1)");
//-- remove all inside SCRIPT and STYLE tags
returnText=returnText.replace(/<script.*>[\w\W]{1,}(.*?)[\w\W]{1,}<\/script>/gi, "");
returnText=returnText.replace(/<style.*>[\w\W]{1,}(.*?)[\w\W]{1,}<\/style>/gi, "");
//-- remove all else
returnText=returnText.replace(/<(?:.|\s)*?>/g, "");
//-- get rid of more than 2 multiple line breaks:
returnText=returnText.replace(/(?:(?:\r\n|\r|\n)\s*){2,}/gim, "\n\n");
//-- get rid of more than 2 spaces:
returnText = returnText.replace(/ +(?= )/g,'');
//-- get rid of html-encoded characters:
returnText=returnText.replace(/ /gi," ");
returnText=returnText.replace(/&/gi,"&");
returnText=returnText.replace(/"/gi,'"');
returnText=returnText.replace(/</gi,'<');
returnText=returnText.replace(/>/gi,'>');
//-- return
document.getElementById("output").value = returnText;
}
It was used with this HTML:
<textarea id="input" style="width: 400px; height: 300px;"></textarea><br />
<button onclick="convertHtmlToText()">CONVERT</button><br />
<textarea id="output" style="width: 400px; height: 300px;"></textarea><br />
/<p.*>/gi
should be /<p.*?>/gi
.
<br>
tags you could use a good regular expression instead: /<br\s*\/?>/
that way you have just one replace instead of 3. Also it seems to me that except for the decoding of entities you can have a single regex, something like this: /<[a-z].*?\/?>/
.
var text = html.replace(/<\/?("[^"]*"|'[^']*'|[^>])*(>|$)/g, "");
This is a regex version, which is more resilient to malformed HTML, like:
Unclosed tags
Some text <img
"<", ">" inside tag attributes
Some text <img alt="x > y">
Newlines
Some <a href="http://google.com">
The code
var html = '<br>This <img alt="a>b" \r\n src="a_b.gif" />is > \nmy<>< > <a>"text"</a'
var text = html.replace(/<\/?("[^"]*"|'[^']*'|[^>])*(>|$)/g, "");
string.replace()
on ONLY the text part, and leave any HTML tags and their attributes unchanged.
const deTagged = myString.replace(/<\/?("[^"]*"|'[^']*'|[^>])*(>|$)/g, ''); const deNewlined = deTagged.replace(/\n/g, '');
from CSS tricks:
https://css-tricks.com/snippets/javascript/strip-html-tags-in-javascript/
const originalString = `
Hey that's somthing
[^<>]
with [^>]
because a valid tag cannot include a <
character, then the XSS vulnerability disappears.
Below code allows you to retain some html tags while stripping all others
function strip_tags(input, allowed) {
allowed = (((allowed || '') + '')
.toLowerCase()
.match(/<[a-z][a-z0-9]*>/g) || [])
.join(''); // making sure the allowed arg is a string containing only tags in lowercase (<a><b><c>)
var tags = /<\/?([a-z][a-z0-9]*)\b[^>]*>/gi,
commentsAndPhpTags = /<!--[\s\S]*?-->|<\?(?:php)?[\s\S]*?\?>/gi;
return input.replace(commentsAndPhpTags, '')
.replace(tags, function($0, $1) {
return allowed.indexOf('<' + $1.toLowerCase() + '>') > -1 ? $0 : '';
});
}
phpjs
). If you use the allowed
param you are vulnerable to XSS: stripTags('<p onclick="alert(1)">mytext</p>', '<p>')
returns <p onclick="alert(1)">mytext</p>
I just needed to strip out the <a>
tags and replace them with the text of the link.
This seems to work great.
htmlContent= htmlContent.replace(/<a.*href="(.*?)">/g, '');
htmlContent= htmlContent.replace(/<\/a>/g, '');
title="..."
.
The accepted answer works fine mostly, however in IE if the html
string is null
you get the "null"
(instead of ''). Fixed:
function strip(html)
{
if (html == null) return "";
var tmp = document.createElement("DIV");
tmp.innerHTML = html;
return tmp.textContent || tmp.innerText || "";
}
A safer way to strip the html with jQuery is to first use jQuery.parseHTML to create a DOM, ignoring any scripts, before letting jQuery build an element and then retrieving only the text.
function stripHtml(unsafe) {
return $($.parseHTML(unsafe)).text();
}
Can safely strip html from:
<img src="unknown.gif" onerror="console.log('running injections');">
And other exploits.
nJoy!
With jQuery you can simply retrieving it by using
$('#elementID').text()
I have created a working regular expression myself:
str=str.replace(/(<\?[a-z]*(\s[^>]*)?\?(>|$)|<!\[[a-z]*\[|\]\]>|<!DOCTYPE[^>]*?(>|$)|<!--[\s\S]*?(-->|$)|<[a-z?!\/]([a-z0-9_:.])*(\s[^>]*)?(>|$))/gi, '');
simple 2 line jquery to strip the html.
var content = "<p>checking the html source </p><p>
</p><p>with </p><p>all</p><p>the html </p><p>content</p>";
var text = $(content).text();//It gets you the plain text
console.log(text);//check the data in your console
cj("#text_area_id").val(text);//set your content to text area using text_area_id
Using Jquery:
function stripTags() {
return $('<p></p>').html(textToEscape).text()
}
input
element support only one line text:
The text state represents a one line plain text edit control for the element's value.
function stripHtml(str) {
var tmp = document.createElement('input');
tmp.value = str;
return tmp.value;
}
Update: this works as expected
function stripHtml(str) {
// Remove some tags
str = str.replace(/<[^>]+>/gim, '');
// Remove BB code
str = str.replace(/\[(\w+)[^\]]*](.*?)\[\/\1]/g, '$2 ');
// Remove html and line breaks
const div = document.createElement('div');
div.innerHTML = str;
const input = document.createElement('input');
input.value = div.textContent || div.innerText || '';
return input.value;
}
Success story sharing
strip("<img onerror='alert(\"could run arbitrary JS here\")' src=bogus>")