join — GTM Variable Template for Array

VARIABLES › ARRAY

join CORE Array

Direct (.tpl) Apply (.tpl)

Joins the elements of an array into a single string, with an optional separator between each element.

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When to Use This

Array Processing

Iterate, filter, map, and reshape arrays of items for batch data operations.

Combining

Merge, concatenate, or join multiple values into a unified result.

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Examples

Join with comma▶ Try

INPUT

Array to Join: ['apple', 'banana', 'orange']
Separator (use {{space}} for space, blank for no separator): ,

OUTPUT

apple,banana,orange

Non-array returns undefined▶ Try

INPUT

Array to Join: not an array
Separator (use {{space}} for space, blank for no separator): ,

OUTPUT

undefined

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GTM Configuration

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join

Read-Only Try Live

Array to Join

💾 The array of elements to join into a string.

Supported formats:
  ✓ Array variable: {{myArrayVariable}}
  ✓ Array literal: ["a", "b", "c"]

Separator (use {{space}} for space, blank for no separator)

💾 The separator string to place between array elements. Spaces are trimmed in GTM fields, so use {{space}} to represent a space character.

Supported formats:
  ✓ String (use {{space}}for space)
  ✓ Empty string (no separator)

Input Setup

Input Function (optional)

⚙️ Optional pre-processing function applied to the array before joining (e.g., filter empty values, transform elements).

Result Handling

Output Function (optional)

⚙️ Optional function to apply to the joined string before returning it (e.g., str => str.toUpperCase(), str => str.trim()). Useful for chaining transformations on the output.

Array to Join array

💡 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 (use {{space}} for space, blank for no separator) string

🔗 Result Handling — Chain Variables

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

join()

+ Chain another variable

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Related Variables

Same category: Array

→ chunk → compact → dropItems → dropItemsRight → every → filterArray → find → findIndexByCallback → findIndexByRegex → flatten → head → includesAll → includesAny → includesNone → indexOf → last → lastIndexOf → reduce → reduceRight → reverse → selectFromArray → some → sort → tail → takeItems → takeItemsRight → uniq → wrapInArray

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Under the Hood

📜 View Implementation Code

/**
 * Joins the elements of an array into a single string, with an optional separator between each element.
 *
 * @param {Array} data.arr - The array of elements to join.
 * @param {string} data.sep - The separator to use between elements.
 * @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 arr before joining.
 * 
 * @returns {string|undefined} The joined string if the input is an array, or undefined if the input is not an array.
 *
 * @framework ggLowCodeGTMKit
 */
const getType = require('getType');

const join = function(array, separator) {
  if (getType(array) === 'array') {
    return array.join(separator);
  }
  return undefined;
};
const safeFunction = fn => typeof fn === 'function' ? fn : x => x;
const out = safeFunction(data.out);
// ===============================================================================
// join - Direct mode
// ===============================================================================
const applyCast = (castFn, value) => safeFunction(castFn)(value);
const processedArray = applyCast(data.pre, data.arr);
return out(join(processedArray, data.sep));
// ===============================================================================
// join(...) – Apply Mode
// ===============================================================================
/*
return function(value, separator) {
   return out(join(value, data.sep));
};
*/

🧪 View Test Scenarios (5 tests)

✅ '[example] Join with comma'
✅ Test joining array with space separator
✅ Test joining array with no separator (empty string)
✅ '[example] Non-array returns undefined'
✅ Test joining array with mixed types