How do I encode HTML special characters using JavaScript?

Other Questions JavaScript
1

I’m looking to output text in HTML format through a function in JavaScript. What methods are available for encoding HTML special characters in JavaScript? Is there a specific API I should use?

2

Use this function to encode HTML special characters:

function encodeHTML(str) {
    const map = {
        '&': '&',
        '<': '&lt;',
        '>': '&gt;',
        '"': '&quot;',
        "'": '&#39;'
    };
    return str.replace(/[&<>"]/g, function(m) { return map[m]; });
}

This will convert characters like < to &lt;. Use it as needed for any HTML content.

3

Encoding HTML special characters in JavaScript is a common task when you want to safely display user-generated content on a web page. The purpose is to convert characters like <, >, and & into their respective HTML entities to prevent security issues, such as Cross-Site Scripting (XSS).

A simple and effective way to encode these characters is by utilizing a manual mapping. Here’s how you can achieve this using a function:

function encodeHTML(str) {
  const map = {
    '&': '&',
    '<': '<',
    '>': '>',
    '"': '"',
    "'": '''
  };
  return str.replace(/[&<>"]'/g, function(m) { return map[m]; });
}

// Example usage:
const userInput = "";

const encodedInput = encodeHTML(userInput);

console.log(encodedInput);

// Output: “<script>alert('XSS');</script>”

In this example, a mapping object, map, is defined where each special character is associated with its corresponding HTML entity. The replace function then uses this map to replace each occurrence of a special character in the input string.

This is particularly useful when dealing with user inputs in web applications to ensure that any special HTML characters are properly encoded to prevent security vulnerabilities.

4

To encode HTML special characters in JavaScript, you can create a function that replaces these characters with their respective HTML entities. This is crucial for preventing cross-site scripting (XSS) attacks by ensuring user input is safely displayed.

Here’s a practical and efficient solution using a simple replacement approach:

function encodeHTML(str) {
  const map = {
    '&': '&amp;',
    '<': '&lt;',
    '>': '&gt;',
    '"': '&quot;',
    "'": '&#039;'
  };
  return str.replace(/[&<>"']/g, function(m) { return map[m]; });
}

// Example usage
const unsafeStr = '<div>Tom & Jerry "The Best"</div>';
const safeStr = encodeHTML(unsafeStr);
console.log(safeStr); // &lt;div&gt;Tom &amp; Jerry &quot;The Best&quot;&lt;/div&gt;

This function maps HTML special characters to their respective encoded forms, ensuring that any user input or dynamic content is safely rendered in HTML. This approach is both effective and easy to implement, making it a great choice for maintaining secure web applications.

5

You can encode HTML special characters using JavaScript by creating a function that replaces them. Here’s a simple approach:

function encodeHTML(str) { return str.replace(/[&<>'"]/g, function(match) { const map = { '&': '&', '<': '<', '>': '>', "'": ''', '"': '"' }; return map[match]; }); }

Use it like this:

const encodedStr = encodeHTML("
content & 'more'
");

This will convert characters like <, >, &, ", and ’ into their respective HTML entities.