Hướng dẫn htmlspecialchars_decode in javascript

Apparently, this is harder to find than I thought it would be. And it even is so simple...

Is there a function equivalent to PHP's htmlspecialchars built into JavaScript? I know it's fairly easy to implement that yourself, but using a built-in function, if available, is just nicer.

For those unfamiliar with PHP, htmlspecialchars translates stuff like into <htmltag/>

I know that escape[] and encodeURI[] do not work this way.

asked Nov 24, 2009 at 1:59

Bart van HeukelomBart van Heukelom

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3

There is a problem with your solution code--it will only escape the first occurrence of each special character. For example:

escapeHtml['Kip\'s evil "test" code\'s here'];
Actual:   Kip's <b>evil "test" code's here
Expected: Kip's <b>evil</b> "test" code's here

Here is code that works properly:

function escapeHtml[text] {
  return text
      .replace[/&/g, "&"]
      .replace[//g, ">"]
      .replace[/"/g, """]
      .replace[/'/g, "'"];
}

Update

The following code will produce identical results to the above, but it performs better, particularly on large blocks of text [thanks jbo5112].

function escapeHtml[text] {
  var map = {
    '&': '&',
    '': '>',
    '"': '"',
    "'": '''
  };
  
  return text.replace[/[&"']/g, function[m] { return map[m]; }];
}

answered Jan 29, 2011 at 5:48

9

That's HTML Encoding. There's no native javascript function to do that, but you can google and get some nicely done up ones.

E.g. //sanzon.wordpress.com/2008/05/01/neat-little-html-encoding-trick-in-javascript/

EDIT:
This is what I've tested:

var div = document.createElement['div'];
  var text = document.createTextNode[''];
  div.appendChild[text];
  console.log[div.innerHTML];

Output: <htmltag/>

answered Nov 24, 2009 at 2:04

o.k.wo.k.w

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7

Worth a read: //bigdingus.com/2007/12/29/html-escaping-in-javascript/

escapeHTML: [function[] {
 var MAP = {
   '&': '&',
   '': '>',
   '"': '"',
   "'": '''
 };
  var repl = function[c] { return MAP[c]; };
  return function[s] {
    return s.replace[/[&'"]/g, repl];
  };
}][]

Note: Only run this once. And don't run it on already encoded strings e.g. & becomes &

answered Mar 13, 2012 at 2:09

Chris JacobChris Jacob

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2

Here's a function to escape HTML:

function escapeHtml[str]
{
    var map =
    {
        '&': '&',
        '': '>',
        '"': '"',
        "'": '''
    };
    return str.replace[/[&"']/g, function[m] {return map[m];}];
}

And to decode:

function decodeHtml[str]
{
    var map =
    {
        '&': '&',
        '<': '',
        '"': '"',
        ''': "'"
    };
    return str.replace[/&|<|>|"|'/g, function[m] {return map[m];}];
}

answered Jan 17, 2017 at 14:01

Dan BrayDan Bray

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With jQuery it can be like this:

var escapedValue = $['
'].text[value].html[];

From related question Escaping HTML strings with jQuery

As mentioned in comment double quotes and single quotes are left as-is for this implementation. That means this solution should not be used if you need to make element attribute as a raw html string.

answered Sep 2, 2010 at 11:51

7

Underscore.js provides a function for this:

_.escape[string]

Escapes a string for insertion into HTML, replacing &, , ", and ' characters.

//underscorejs.org/#escape

It's not a built-in JavaScript function, but if you are already using Underscore.js, it is a better alternative than writing your own function if your strings to convert are not too large.

answered Jun 2, 2014 at 12:14

mer10z_techmer10z_tech

6977 silver badges12 bronze badges

2

Yet another take at this is to forgo all the character mapping altogether and to instead convert all unwanted characters into their respective numeric character references, e.g.:

function escapeHtml[raw] {
    return raw.replace[/[&"']/g, function onReplace[match] {
        return '&#' + match.charCodeAt[0] + ';';
    }];
}

Note that the specified RegEx only handles the specific characters that the OP wanted to escape but, depending on the context that the escaped HTML is going to be used, these characters may not be sufficient. Ryan Grove’s article There's more to HTML escaping than &, , and " is a good read on the topic. And depending on your context, the following RegEx may very well be needed in order to avoid XSS injection:

var regex = /[&"'` !@$%[]=+{}[\]]/g

answered Sep 8, 2014 at 16:48

FredricFredric

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Chances are you don't need such a function. Since your code is already in the browser*, you can access the DOM directly instead of generating and encoding HTML that will have to be decoded backwards by the browser to be actually used.

Use innerText property to insert plain text into the DOM safely and much faster than using any of the presented escape functions. Even faster than assigning a static preencoded string to innerHTML.

Use classList to edit classes, dataset to set data- attributes and setAttribute for others.

All of these will handle escaping for you. More precisely, no escaping is needed and no encoding will be performed underneath**, since you are working around HTML, the textual representation of DOM.

// use existing element
var author = 'John "Superman" Doe ';
var el = document.getElementById['first'];
el.dataset.author = author;
el.textContent = 'Author: '+author;

// or create a new element
var a = document.createElement['a'];
a.classList.add['important'];
a.href = '/search?q=term+"exact"&n=50';
a.textContent = 'Search for "exact" term';
document.body.appendChild[a];

// actual HTML code
console.log[el.outerHTML];
console.log[a.outerHTML];

.important { color: red; }

* This answer is not intended for server-side JavaScript users [Node.js, etc.]

** Unless you explicitly convert it to actual HTML afterwards. E.g. by accessing innerHTML - this is what happens when you run $['

String.prototype.escapeHTML = function[] {
        return this.replace[/&/g, "&"]
                   .replace[//g, ">"]
                   .replace[/"/g, """]
                   .replace[/'/g, "'"];
    }

var toto = "test
";
alert[toto.escapeHTML[]];

function htmlEscape[str]{
    return str.replace[/[&'"]/g,x=>'&#'+x.charCodeAt[0]+';']
}