extractNumber — GTM Variable Template for String

VARIABLES › STRING

extractNumber CORE String

Direct (.tpl) Apply (.tpl)

Extracts the first number found in a string (including decimals and negatives). Returns undefined if no number is found.

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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.

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Examples

Extract integer from text▶ Try

INPUT

String To Search: The price is 42 dollars

OUTPUT

42

Extract decimal number▶ Try

INPUT

String To Search: Temperature is 36.5 degrees

OUTPUT

36.5

No numbers returns undefined▶ Try

INPUT

String To Search: No numbers here

OUTPUT

undefined

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GTM Configuration

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extractNumber

Read-Only Try Live

String To Search

💾 The string to search for numbers.

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 Search 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]

🔗 Result Handling — Chain Variables

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

extractNumber()

+ Chain another variable

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Related Variables

Same category: String

→ assignParamsToString → charAt → concatenateValues → countWordsInString → endsWith → extract → extractFirstSegment → 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

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Under the Hood

📜 View Implementation Code

/**
 * Extracts the first number found in a string.
 *
 * @param {string} data.src - The string to search for numbers.
 * @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 {number|undefined} The first number found, or undefined if no number is found.
 *
 * @framework ggLowCodeGTMKit
 */

const makeNumber = require('makeNumber');

const extractNumber = function(stringToMatch) {
    if (typeof stringToMatch !== 'string') { 
        return undefined; 
    }
    const match = stringToMatch.match("-?\\d+(\\.\\d+)?");
    if (match) {
        return makeNumber(match[0]);
    }
    return undefined;
};

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

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

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

🧪 View Test Scenarios (5 tests)

✅ '[example] Extract integer from text'
✅ '[example] Extract decimal number'
✅ String with negative number - should extract negative number
✅ '[example] No numbers returns undefined'
✅ Non-string input - should return undefined