Encode/Decode HTML

01-06-2019

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If you want to display html code on a website, you can’t just type a < in you index.html and expect it to show up. You have to use an equivalent html entity instead.

Client-side (Javascript)

The following javascript function is a handy way of encoding and decoding html, so you can display the code on your website.

window.htmlentities = {
 encode: function (str) {
  var buf = [];
  for (var i = str.length - 1; i >= 0; i--) {
   buf.unshift(["&#", str[i].charCodeAt(), ";"].join(""));
  }
  return buf.join("");
 },
 decode: function (str) {
  return str.replace(/&#(\d+);/g, function (match, dec) {
   return String.fromCharCode(dec);
  });
 },
};

Encode

htmlentities.encode(
 "Hello, this is a test stríng > < with characters that could break html. Therefore we convert it to its html characters."
);

Output: “Hello, this is a test stríng > < with characters that could break html. Therefore we convert it to its html characters.”

Decode

htmlentities.decode(
 "Hello, this is a test stríng > < with characters that could break html. Therefore we convert it to its html characters."
);

Output: “Hello, this is a test stríng > < with characters that could break html. Therefore we convert it to its html characters.”

Server-side (PHP)

If you need to convert html entities serverside, this can easily be done with PHP like so:

<?php
    $converted_html = htmlspecialchars("<a href='test'>Test</a>", ENT_QUOTES);
    echo $converted_html; // &lt;a href=&#039;test&#039;&gt;Test&lt;/a&gt;
?>