parseValue — GTM Variable Template for Value

VARIABLES › VALUE

parseValue EXTENDED Value

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

Converts a string representation back to its original data type (boolean, number, null , etc.). Supports primitive types and optional JSON parsing.

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When to Use This

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Examples

Parse string to boolean▶ Try

INPUT

String To Parse: true
Enable JSON Parsing: false

OUTPUT

true

Parse string to number▶ Try

INPUT

String To Parse: 42
Enable JSON Parsing: false

OUTPUT

42

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Live Sandbox

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parseValue

Read-Only Try Live

String To Parse

Parses a string value into its native type (boolean, number, etc.).

*** Parse string to boolean***
Input: String To Parse: true
jsn: false
↪️ Output: true

*** Parse string to number***
Input: String To Parse: 42
jsn: false
↪️ Output: 42

Advanced Setting

Enable JSON Parsing

☑️ If enabled, attempts to parse JSON-like strings for complex data types (objects, arrays).

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 Parse 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.

parseValue()

+ Chain another variable

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Related Variables

Same category: Value

→ NaN → apply → applyChain → emptyArray → emptyObject → emptyObjectArray → emptyString → false → falseTo → falsyTo → filterValue → getLength → getType → identity → mapTruthiness → not → null → nullTo → regexTableLookupAll → regexTableLookupCallback → true → undefinedTo → zero

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Under the Hood

📜 View Implementation Code

/**
 * Converts a string representation back to its original data type.
 *
 * @param {string} data.src - The string to be converted back to its original value.
 * @param {boolean} data.jsn - If true, attempts to parse JSON-like strings.
 * @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 conversion.
 *
 * @returns {any} The original value corresponding to the string representation.
 *
 * @framework ggLowCodeGTMKit
 */
const makeNumber = require('makeNumber');

const parseValue = function(value, enableJSONParsing) {
    if (typeof value !== 'string') { return value; }
    if (value === 'true') return true;
    if (value === 'false') return false;
    if (value === 'null') return null;
    if (value === 'undefined') return undefined;
    if (value === 'NaN') return 0/0;
    if (value === 'Infinity') return 1/0;
    if (value === '-Infinity') return -1/0;

    const number = makeNumber(value);
    if (typeof number === 'number' && number === number) return number;

    if (enableJSONParsing) {
        const JSON = require('JSON');
        if (JSON.parse(value) !== undefined) return JSON.parse(value);
    }

    return value;
};
const safeFunction = fn => typeof fn === 'function' ? fn : x => x;
const out = safeFunction(data.out);
// ===============================================================================
// parseValue - Direct mode
// ===============================================================================
const applyCast = (castFn, value) => safeFunction(castFn)(value);
const value = applyCast(data.pre, data.src);
return out(parseValue(value, data.jsn));
// ===============================================================================
// parseValue(...) – Apply Mode
// ===============================================================================
/*
return function(value, enableJSONParsing) {
   enableJSONParsing = data.rp1 ? enableJSONParsing : data.jsn;
   return out(parseValue(value, enableJSONParsing));
};
*/

🧪 View Test Scenarios (5 tests)

✅ '[example] Parse string to boolean'
✅ String 'false' - should convert to boolean false
✅ '[example] Parse string to number'
✅ Non-parseable string - should return unchanged
✅ String 'null' - should convert to null