如何使用 jQuery 解码 HTML 实体？

Question

How do I use jQuery to decode HTML entities in a string?

Answer 1

Security note: using this answer (preserved in its original form below) may introduce an XSS vulnerability into your application. You should not use this answer. Read lucascaro's answer for an explanation of the vulnerabilities in this answer, and use the approach from either that answer or Mark Amery's answer instead.

Actually, try

 var encodedStr = "This is fun &amp; stuff"; var decoded = $("<div/>").html(encodedStr).text(); console.log(decoded);

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <div/>

Answer 2

Without any jQuery:

 function decodeEntities(encodedString) { var textArea = document.createElement('textarea'); textArea.innerHTML = encodedString; return textArea.value; } console.log(decodeEntities('1 & 2')); // '1 & 2'

This works similarly to the accepted answer , but is safe to use with untrusted user input.

---

Security issues in similar approaches

As noted by Mike Samuel , doing this with a <div> instead of a <textarea> with untrusted user input is an XSS vulnerability, even if the <div> is never added to the DOM:

 function decodeEntities(encodedString) { var div = document.createElement('div'); div.innerHTML = encodedString; return div.textContent; } // Shows an alert decodeEntities('<img src="nonexistent_image" onerror="alert(1337)">')

However, this attack is not possible against a <textarea> because there are no HTML elements that are permitted content of a <textarea> . Consequently, any HTML tags still present in the 'encoded' string will be automatically entity-encoded by the browser.

 function decodeEntities(encodedString) { var textArea = document.createElement('textarea'); textArea.innerHTML = encodedString; return textArea.value; } // Safe, and returns the correct answer console.log(decodeEntities('<img src="nonexistent_image" onerror="alert(1337)">'))

Warning : Doing this using jQuery's .html() and .val() methods instead of using .innerHTML and .value is also insecure* for some versions of jQuery, even when using a textarea . This is because older versions of jQuery would deliberately and explicitly evaluate scripts contained in the string passed to .html() . Hence code like this shows an alert in jQuery 1.8:

 //<.-- CDATA // Shows alert $("<textarea>");html("<script>alert(1337).</script>");text(); //-->

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.2.3/jquery.min.js"></script>

_{* Thanks to Eru Penkman for catching this vulnerability.}

Answer 3

Like Mike Samuel said, don't use jQuery.html().text() to decode html entities as it's unsafe.

Instead, use a template renderer like Mustache.js or decodeEntities from @VyvIT's comment.

Underscore.js utility-belt library comes with escape and unescape methods, but they are not safe for user input:

_.escape(string)

_.unescape(string)

Answer 4

I think you're confusing the text and HTML methods. Look at this example, if you use an element's inner HTML as text, you'll get decoded HTML tags (second button). But if you use them as HTML, you'll get the HTML formatted view (first button).

<div id="myDiv">
    here is a <b>HTML</b> content.
</div>
<br />
<input value="Write as HTML" type="button" onclick="javascript:$('#resultDiv').html($('#myDiv').html());" />
&nbsp;&nbsp;
<input value="Write as Text" type="button" onclick="javascript:$('#resultDiv').text($('#myDiv').html());" />
<br /><br />
<div id="resultDiv">
    Results here !
</div>

First button writes: here is a HTML content.

Second button writes: here is a <B>HTML</B> content.

By the way, you can see a plug-in that I found in jQuery plugin - HTML decode and encode that encodes and decodes HTML strings.

Answer 5

The question is limited by 'with jQuery' but it might help some to know that the jQuery code given in the best answer here does the following underneath...this works with or without jQuery:

function decodeEntities(input) {
  var y = document.createElement('textarea');
  y.innerHTML = input;
  return y.value;
}

Answer 6

You can use the he library, available from https://github.com/mathiasbynens/he

Example:

console.log(he.decode("Jörg &amp Jürgen rocked to & fro "));
// Logs "Jörg & Jürgen rocked to & fro"

I challenged the library's author on the question of whether there was any reason to use this library in clientside code in favour of the <textarea> hack provided in other answers here and elsewhere. He provided a few possible justifications:

• If you're using node.js serverside, using a library for HTML encoding/decoding gives you a single solution that works both clientside and serverside.

• Some browsers' entity decoding algorithms have bugs or are missing support for some named character references . For example, Internet Explorer will both decode and render non-breaking spaces (   ) correctly but report them as ordinary spaces instead of non-breaking ones via a DOM element's innerText property, breaking the <textarea> hack (albeit only in a minor way). Additionally, IE 8 and 9 simply don't support any of the new named character references added in HTML 5. The author of he also hosts a test of named character reference support athttp://mathias.html5.org/tests/html/named-character-references/ . In IE 8, it reports over one thousand errors.

  If you want to be insulated from browser bugs related to entity decoding and/or be able to handle the full range of named character references, you can't get away with the <textarea> hack; you'll need a library like he .

• He just darn well feels like doing things this way is less hacky.

Answer 7

encode:

 $("<textarea/>").html('<a>').html(); // return '&lt;a&gt'

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <textarea/>

decode:

 $("<textarea/>").html('&lt;a&gt').val() // return '<a>'

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <textarea/>

Answer 8

Try this:

 var htmlEntities = "<script>alert('hello');</script>"; var htmlDecode =$.parseHTML(htmlEntities)[0]['wholeText']; console.log(htmlDecode);

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

parseHTML is a Function in Jquery library and it will return an array that includes some details about the given String..

in some cases the String is being big, so the function will separate the content to many indexes..

and to get all the indexes data you should go to any index, then access to the index called "wholeText".

I chose index 0 because it's will work in all cases (small String or big string).

Answer 9

Use

myString = myString.replace( /\&/g, '&' );

It is easiest to do it on the server side because apparently JavaScript has no native library for handling entities, nor did I find any near the top of search results for the various frameworks that extend JavaScript.

Search for "JavaScript HTML entities", and you might find a few libraries for just that purpose, but they'll probably all be built around the above logic - replace, entity by entity.

Answer 10

You have to make custom function for html entities:

function htmlEntities(str) {
return String(str).replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g,'&gt;').replace(/"/g, '&quot;');
}

Answer 11

Suppose you have below String.

Our Deluxe cabins are warm, cozy &amp; comfortable

var str = $("p").text(); // get the text from <p> tag
$('p').html(str).text();  // Now,decode html entities in your variable i.e 

str and assign back to

tag.

that's it.

Answer 12

For ExtJS users, if you already have the encoded string, for example when the returned value of a library function is the innerHTML content, consider this ExtJS function:

Ext.util.Format.htmlDecode(innerHtmlContent)

Answer 13

I just had to have an HTML entity charater (⇓) as a value for a HTML button. The HTML code looks good from the beginning in the browser:

<input type="button" value="Embed & Share  &dArr;" id="share_button" />

Now I was adding a toggle that should also display the charater. This is my solution

$("#share_button").toggle(
    function(){
        $("#share").slideDown();
        $(this).attr("value", "Embed & Share " + $("<div>").html("&uArr;").text());
    }

This displays ⇓ again in the button. I hope this might help someone.

Answer 14

Extend a String class:

String::decode = ->
  $('<textarea />').html(this).text()

and use as method:

"<img src='myimage.jpg'>".decode()

Answer 15

You don't need jQuery to solve this problem, as it creates a bit of overhead and dependency.

I know there are a lot of good answers here, but since I have implemented a bit different approach, I thought to share.

This code is a perfectly safe security-wise approach, as the escaping handler depends on the browser, instead on the function. So, if some vulnerability will be discovered in the future, this solution is covered.

const decodeHTMLEntities = text => {
    // Create a new element or use one from cache, to save some element creation overhead
    const el = decodeHTMLEntities.__cache_data_element 
             = decodeHTMLEntities.__cache_data_element 
               || document.createElement('div');
    
    const enc = text
        // Prevent any mixup of existing pattern in text
        .replace(/⪪/g, '⪪#')
        // Encode entities in special format. This will prevent native element encoder to replace any amp characters
        .replace(/&([a-z1-8]{2,31}|#x[0-9a-f]+|#\d+);/gi, '⪪$1⪫');

    // Encode any HTML tags in the text to prevent script injection
    el.textContent = enc;

    // Decode entities from special format, back to their original HTML entities format
    el.innerHTML = el.innerHTML
        .replace(/⪪([a-z1-8]{2,31}|#x[0-9a-f]+|#\d+)⪫/gi, '&$1;')
        .replace(/⪪#/g, '⪪');
   
    // Get the decoded HTML entities
    const dec = el.textContent;
    
    // Clear the element content, in order to preserve a bit of memory (in case the text is big)
    el.textContent = '';

    return dec;
}

// Example
console.log(decodeHTMLEntities("<script>alert('&awconint;&CounterClockwiseContourIntegral;&#x02233;&#8755;⪪#x02233⪫');</script>"));
// Prints: <script>alert('∳∳∳∳⪪#x02233⪫');</script>

By the way, I have chosen to use the characters ⪪ and ⪫ , because they are rarely used, so the chance of impacting the performance by matching them is significantly lower.

Answer 16

Here are still one problem: Escaped string does not look readable when assigned to input value

var string = _.escape("<img src=fake onerror=alert('boo!')>");
$('input').val(string);

Exapmle: https://jsfiddle.net/kjpdwmqa/3/

Answer 17

Alternatively, theres also a library for it..

here, https://cdnjs.com/libraries/he

npm install he                 //using node.js

<script src="js/he.js"></script>  //or from your javascript directory

The usage is as follows...

//to encode text 
he.encode('© Ande & Nonso® Company LImited 2018');  

//to decode the 
he.decode('© Ande & Nonso® Company Limited 2018');

cheers.

Answer 18

To decode HTML Entities with jQuery, just use this function:

function html_entity_decode(txt){
    var randomID = Math.floor((Math.random()*100000)+1);
    $('body').append('<div id="random'+randomID+'"></div>');
    $('#random'+randomID).html(txt);
    var entity_decoded = $('#random'+randomID).html();
    $('#random'+randomID).remove();
    return entity_decoded;
}

How to use:

Javascript:

var txtEncoded = "á é í ó ú";
$('#some-id').val(html_entity_decode(txtEncoded));

HTML:

<input id="some-id" type="text" />

Answer 19

The easiest way is to set a class selector to your elements an then use following code:

$(function(){
    $('.classSelector').each(function(a, b){
        $(b).html($(b).text());
    });
});

Nothing any more needed!

I had this problem and found this clear solution and it works fine.

Answer 20

I think that is the exact opposite of the solution chosen.

var decoded = $("<div/>").text(encodedStr).html();