extractFirstSegment — GTM Variable Template for String

VARIABLES › STRING

extractFirstSegment CORE String

Direct (.tpl) Apply (.tpl)

Returns the first part of a string split by a given separator. If the input is not a valid string, the original value is returned.

---

When to Use This

String Manipulation

Transform, clean, and normalize text data for consistent downstream processing.

Extraction

Pull specific values, segments, or patterns from complex data structures.

---

Examples

Split by comma▶ Try

INPUT

String To Split: hello-world-test
Separator: -

OUTPUT

hello

Email username extraction▶ Try

INPUT

String To Split: user@example.com
Separator: @

OUTPUT

user

Non-string input returns original▶ Try

INPUT

String To Split: 12345
Separator: -

OUTPUT

12345

---

GTM Configuration

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

extractFirstSegment

Read-Only Try Live

String To Split

Returns the first part of a string split by a given separator. If the input is not a valid string, the original value is returned.

*** Split by comma***
Input: String To Split: hello-world-test
Separator: -
↪️ Output: hello

*** Email username extraction***
Input: String To Split: user@example.com
Separator: @
↪️ Output: user

*** Non-string input returns original***
Input: String To Split: 12345
Separator: -
↪️ Output: 12345

Separator

💾 The separator to use for splitting the string.

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.

String To Split string

💡 Type any text to see the result update live

🎯 Using special value — click input to type instead

Test with:

Falsy undefined null "" empty 0 false NaN

Truthy true 42 "hello" {} empty [] empty {a:1} [1,2,3]

Separator string

🔗 Result Handling — Chain Variables

Chain apply-mode variables to the output. Each variable receives the result of the previous one.

extractFirstSegment()

+ Chain another variable

---

Related Variables

Same category: String

→ assignParamsToString → charAt → concatenateValues → countWordsInString → endsWith → extract → extractNumber → fromBase64 → indexOf → left → matchAll → matchRegex → omitParamsFromString → padEnd → padStart → pickParamsFromString → replaceAll → replaceAllWithRegex → replaceFirst → right → safeSplit → sanitizeTextAndRemoveHtml → sanitizeTextLite → search → slice → split → startsWith → test → toBase64 → toCamelCase → toJsonString → toKebabCase → toLocaleLowerCase → toLocaleUpperCase → toLowerCase → toNumber → toSnakeCase → toStartCase → toString → toStringRepresentation → toUpperCase → toUpperFirst → trim → trimEnd → trimStart → truncate

---

Under the Hood

📜 View Implementation Code

/**
 * Returns the first part of a string split by a given separator.
 * If the input is not a valid string, the original value is returned.
 *
 * @param {string} data.src - The string to split.
 * @param {string} data.sep - The separator to use for splitting the string.
 * @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 splitting.
 * 
 * @returns {string} The first segment of the split string, or the original value if input is not a string.
 *
 * @framework ggLowCodeGTMKit
 */
const extractFirstSegment = function(inputString, separator) {
    if (typeof inputString !== 'string') {
        return inputString;
    }
    const parts = inputString.split(separator);
    return parts[0];
};
const safeFunction = fn => typeof fn === 'function' ? fn : x => x;
const out = safeFunction(data.out);
// ===============================================================================
// extractFirstSegment - Direct mode
// ===============================================================================
const applyCast = (castFn, value) => safeFunction(castFn)(value);
const value = applyCast(data.pre, data.src);
return out(extractFirstSegment(value, data.sep));
// ===============================================================================
// extractFirstSegment(...) – Apply Mode
// ===============================================================================
/*
return function(value, separator) {
   separator = data.rp1 ? data.sep : separator;
   return out(extractFirstSegment(value, separator));
};
*/

🧪 View Test Scenarios (5 tests)

✅ '[example] Split by comma'
✅ String without separator - should return original string
✅ '[example] Email username extraction'
✅ String starting with separator - should return empty string
✅ '[example] Non-string input returns original'