nullTo — GTM Variable Template for Value

VARIABLES › VALUE

nullTo CORE Value

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

Replaces null values with a default. Non-null values pass through unchanged.

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When to Use This

Value Utilities

Handle edge cases — defaults for undefined/null, type checks, coercion.

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Examples

String passes through▶ Try

INPUT

Value To Check: hello
Default Value: default

OUTPUT

hello

Null returns default▶ Try

INPUT

Value To Check: null
Default Value: default

OUTPUT

default

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Live Sandbox

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nullTo

Read-Only Try Live

Value To Check

💾 The value to check for null.

Supported formats:
  ✓ Any

Default Value

💾 The default value to return if the source value is null.

Supported formats:
  ✓ Any

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.

Value To Check any

💡 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]

Default Value any

🔗 Result Handling — Chain Variables

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

nullTo()

+ 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 → parseValue → regexTableLookupAll → regexTableLookupCallback → true → undefinedTo → zero

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Under the Hood

📜 View Implementation Code

/**
 * Replaces null with a specific default value.
 *
 * @param {any} data.src - The value to check.
 * @param {any} data.def - The default value to return if the value is null.
 * @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 checking.
 *
 * @returns {any} Returns the original value if it's not null, otherwise returns the default value.
 *
 * @framework ggLowCodeGTMKit
 */
const nullTo = function(value, defaultValue) {
    return value === null ? defaultValue : value;
};
const safeFunction = fn => typeof fn === 'function' ? fn : x => x;
const out = safeFunction(data.out);
// ===============================================================================
// nullTo - Direct mode
// ===============================================================================
const applyCast = (castFn, value) => safeFunction(castFn)(value);
const value = applyCast(data.pre, data.src);
return out(nullTo(value, data.def));
// ===============================================================================
// nullTo(...) – Apply Mode
// ===============================================================================
/*
return function(value, defaultValue) {
   defaultValue = data.rp1 ? defaultValue : data.def;
   return out(nullTo(value, defaultValue));
};
*/

🧪 View Test Scenarios (5 tests)

✅ Undefined value - returns original value
✅ '[example] String passes through'
✅ Zero value - returns original zero value
✅ '[example] Null returns default'
✅ False value - returns original false value