extractProtocol — GTM Variable Template for URL

VARIABLES › URL

extractProtocol EXTENDED URL

Direct (.tpl) Apply (.tpl) Add to GTM

Extracts the protocol from a URL.

---

When to Use This

---

Examples

Extract HTTPS protocol

INPUT

URL: https://example.com/path

OUTPUT

https:

Extract HTTP protocol

INPUT

URL: http://localhost:8080/api

OUTPUT

http:

---

GTM Configuration

This is what you'll see when you open this variable in Google Tag Manager. Hover the icons for details.

Read-only Preview

extractProtocol

URL

💾 The URL to extract the protocol from.

Supported formats:
  ✓ String

Input Setup

Input Function (optional)

⚙️ Optional pre-processing function applied to the input before internal logic (e.g., convert object to string, normalize case). Internal transformations such as case handling will still apply afterward.

Result Handling

Output Function (optional)

⚙️ Optional function to apply to the result before returning it (e.g., str => str + ' €', val => val !== undefined for boolean conversion). Useful for chaining transformations on the output.

---

Related Variables

Same category: URL

→ assignParamsToString → buildUrlFromParts → completeUrl → decodeUri → decodeUriComponent → encodeURIComponent → encodeUri → extractHash → extractHashParams → extractHost → extractHostname → extractOrigin → extractPasword → extractPathname → extractPort → extractSearch → extractSearchParams → extractSegmentByIndex → extractUserName → hasFragment → hasParameterWithValue → hasQueryString → omitParamsFromString → parseUrlComponents → pickParamsFromString → stringToPath → ⚡ URL › Transformer

---

Under the Hood

📜 View Implementation Code

/**
 * Extracts the protocol from a given URL.
 *
 * @param {string} data.src - The URL to extract the protocol from.
 * @param {Function|string} [data.out] - Optional output handler: function to transform result or string with format.
 *
 * Direct-mode specific parameters:
 * @param {Function} [data.pre] - Optional pre-processor function to transform src before extracting.
 *
 * @returns {string|undefined} The protocol of the URL, or undefined if the input is invalid.
 *
 * @framework ggLowCodeGTMKit
 */

const parseUrl = require('parseUrl');

const extractProtocol = function(url) {
    const parsed = parseUrl(url);
    return parsed && parsed.protocol || undefined;
};

const safeFunction = fn => typeof fn === 'function' ? fn : x => x;
const out = safeFunction(data.out);

// ===============================================================================
// extractProtocol - Direct mode
// ===============================================================================
const applyCast = (castFn, value) => safeFunction(castFn)(value);
const value = applyCast(data.pre, data.src);
return out(extractProtocol(value));

// ===============================================================================
// extractProtocol() – Apply Mode
// ===============================================================================
/*
return function(value) {
   return out(extractProtocol(value));
};
*/

🧪 View Test Scenarios (5 tests)

✅ '[example] Extract HTTPS protocol'
✅ '[example] Extract HTTP protocol'
✅ FTP URL - extracts ftp protocol
✅ Invalid URL - returns undefined
✅ Empty string input - returns undefined