Question 1

What is URL encoding?

Accepted Answer

URL encoding (percent-encoding) converts unsafe characters into %XX format where XX is hex value. Space becomes %20, & becomes %26. Only alphanumeric and -_.!~*'() are safe. Encoding ensures URLs work correctly across browsers, servers, and APIs without breaking due to special characters.

Question 2

What is the difference between encodeURI and encodeURIComponent?

Accepted Answer

encodeURI encodes for full URLs, preserving reserved chars: /?:@&=+$,#. encodeURIComponent encodes for query parameters, encoding ALL special chars. Use encodeURI for 'https://example.com/path', encodeURIComponent for query values like 'search?q=' + encodeURIComponent(userInput).

Question 3

Why do spaces become %20 or +?

Accepted Answer

%20 is standard URL encoding for space (hex 20). + is legacy form encoding from application/x-www-form-urlencoded. In URLs and URI components, use %20. In form submissions, + is acceptable. decodeURIComponent handles both. Modern APIs expect %20.

Question 4

When should I encode query parameters?

Accepted Answer

Always encode query parameter values: user input, search terms, IDs, any data that might contain spaces, symbols, or Unicode. Encode the value only, not the key or = or & separators. Example: '?q=' + encodeURIComponent('hello world') gives '?q=hello%20world'.

Question 5

How do I encode Unicode characters?

Accepted Answer

encodeURIComponent handles Unicode automatically: '日本' becomes '%E6%97%A5%E6%9C%AC' (UTF-8 encoded as multiple percent-escaped bytes). JavaScript's encode functions use UTF-8. Each Unicode char becomes 2-4 %XX sequences. decodeURIComponent reverses correctly.

URL Encoder & Decoder

Encoded Result

Quick Examples

Common Encodings

Use Cases