Question 1

What are the components of a URL?

Accepted Answer

A full URL has these components: scheme (https://), authority (user:password@host:port), path (/path/to/page), query (?key=value&key2=value2), and fragment (#section). Example: https://user:pass@example.com:8080/api/v1/users?sort=name&page=2#results. The scheme and host are required; all others are optional. In browsers, the fragment (#) is never sent to the server — it is processed client-side only.

Question 2

What is the difference between a URL, URI, and URN?

Accepted Answer

A URI (Uniform Resource Identifier) is the broadest term — any string that identifies a resource. A URL (Uniform Resource Locator) is a URI that includes the location/protocol to retrieve the resource (https://, ftp://, mailto:). A URN (Uniform Resource Name) identifies a resource by name without location, e.g. urn:isbn:0451450523. In practice, 'URL' is used colloquially to mean any web address, and the distinction between URL and URI rarely matters for web development.

Question 3

What is the difference between URL encoding and URL parsing?

Accepted Answer

URL parsing splits a URL into its structural components (scheme, host, path, query, fragment). URL encoding (percent-encoding) converts special characters in URL components to %XX format — e.g. spaces become %20, & becomes %26 when it appears in a value rather than as a parameter separator. They work together: parse first to identify components, then decode each component's percent-encoding to get the actual values. In JavaScript, use new URL(str) to parse and URLSearchParams to decode query parameters.

Question 4

How do I parse a URL in JavaScript?

Accepted Answer

Use the built-in URL API: const url = new URL('https://example.com/path?key=value#hash'). Properties: url.protocol ('https:'), url.hostname ('example.com'), url.port (''), url.pathname ('/path'), url.search ('?key=value'), url.hash ('#hash'), url.searchParams.get('key') ('value'). The URL constructor throws for invalid URLs. For relative URLs, provide a base: new URL('/path', 'https://example.com'). Available in all modern browsers and Node.js 10+.

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