unescapeHTML
Unescapes HTML entities back to their original characters.
1/**
2 * Unescapes HTML entities back to their original characters.
3 *
4 * @param str - The input string containing escaped HTML entities.
5 * @returns The unescaped string.
6 */
7export function unescapeHTML(str: string): string {
8 return str.replace(
9 /&(amp|lt|gt|quot|#39);/g,
10 (_, entity) =>
11 ({
12 amp: '&',
13 lt: '<',
14 gt: '>',
15 quot: '"',
16 '#39': "'",
17 }[entity] || entity)
18 );
19}Reverses HTML Escaping
Accurately restores previously escaped special characters, ensuring correct display of original content.
Targeted and Safe
Only replaces known entities, avoiding overcorrection or unintended replacements.
Simple and Readable Implementation
The use of a clear regex and a mapping object makes the logic easy to follow and maintain.
Lightweight Alternative to DOM Parsing
Provides a faster and less resource-intensive solution than using
innerHTMLor a temporary DOM element.
Tests | Examples
1test('unescapeHTML - unescapes all common HTML entities', () => {
2 expect(
3 unescapeHTML('<div class="test">Tom & Jerry</div>')
4 ).toBe('<div class="test">Tom & Jerry</div>');
5});
6
7test("unescapeHTML - unescapes single quote entity", () => {
8 expect(unescapeHTML('It's a test')).toBe("It's a test");
9});
10
11test('unescapeHTML - handles string without HTML entities', () => {
12 expect(unescapeHTML('No escaping needed')).toBe('No escaping needed');
13});
14
15test('unescapeHTML - handles empty string', () => {
16 expect(unescapeHTML('')).toBe('');
17});
18
19test('unescapeHTML - ignores unknown entities', () => {
20 expect(unescapeHTML('Fish &unknown; < sea')).toBe('Fish &unknown; < sea');
21});Common Use Cases
Rendering Stored User Input
Convert stored HTML-safe text back to readable characters for display.
Processing Escaped Server Responses
Decode escaped strings returned from APIs, databases, or logs before presenting them to users.
Reversing Sanitized Content for Editing
Restore HTML characters when loading content into a WYSIWYG editor or input field.
Displaying Raw HTML Examples
Decode strings when switching from code-preview to rendered mode in educational tools or documentation platforms.