itemFilterByProperty — GTM Variable Template for Items

VARIABLES › ITEMS

itemFilterByProperty EXTENDED Items

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

Filters an array of items, keeping only the objects that match the specified property and value.

---

Examples

Filter by value▶ Try

INPUT

Items (Array of Objects): [{cat: "A", v: 1}, {cat: "B", v: 2}]
Property Name: cat
Match Value (Optional): A

OUTPUT

[{cat: "A", v: 1}]

Filter with a predicate function▶ Try

INPUT

Items (Array of Objects): [{name: "Shirt", price: 30}, {name: "Jacket", price: 120}, {name: "Hat", price: 15}]
Property Name: price
Match Value (Optional): x => x > 50

OUTPUT

[{name: "Jacket", price: 120}]

---

Live Sandbox

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

itemFilterByProperty

Read-Only Try Live

Items (Array of Objects)

💾 Array of objects to filter.

Supported formats:
  ✓ Array

Property Name

💾 Property name to check in each object.

Supported formats:
  ✓ String

Match Value (Optional)

🎯 The value that the property must equal to be included, or a predicate function (e.g. x => x > 50).

Supported formats:
  ✓ Any
  ✓ Function

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.

Items (Array of Objects) 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]

Property Name string

Match Value (Optional) any

🔗 Result Handling — Chain Variables

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

itemFilterByProperty()

+ Chain another variable

---

Related Variables

Same category: Items

→ itemAssignDefaults → itemMapProperty → itemOmit → itemSet → itemSplitProperty → itemUniqByProperty → pluckProperty → sumProductOfProperties → sumProperty → sumPropertyNested → ⚡ ITEMS › Transformer

---

Under the Hood

📜 View Implementation Code

/**
 * Filters an array of objects (items) returning only those where the specified property matches the provided value or satisfies a predicate function.
 *
 * @param {Array} data.src - Array of objects to filter.
 * @param {string} data.prp - Property name to check.
 * @param {any|Function} [data.val] - The expected value of the property, or a predicate function (e.g. x => x > 50).
 * @param {Function|string} [data.out] - Optional output handler.
 *
 * Direct-mode specific parameters:
 * @param {Function} [data.pre] - Optional pre-processor function to transform src before processing.
 *
 * @returns {Array} Filtered array of objects.
 *
 * @framework ggLowCodeGTMKit
 */
const getType = require('getType');

const itemFilterByProperty = function(items, property, predicate) {
    if (getType(items) !== 'array') return [];

    const safePredicate = function(val) {
        return getType(val) === 'function' ? val : function(x) { return val === x; };
    };

    const check = safePredicate(predicate);

    return items.filter(function(item) {
        if (!item || item[property] === undefined) return false;
        return check(item[property]);
    });
};

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

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

// ===============================================================================
// itemFilterByProperty(...) - Apply Mode
// ===============================================================================
/*
return function(value, property, predicate) {
   property = data.rp1 ? property : data.prp;
   predicate = data.rp2 ? predicate : data.val;
   return out(itemFilterByProperty(value, property, predicate));
};
*/

🧪 View Test Scenarios (3 tests)

✅ '[example] Filter by value'
✅ '[example] Filter with a predicate function'
✅ Empty array returns empty