charAt — GTM Variable Template for String

VARIABLES › STRING

charAt EXTENDED String

Direct (.tpl) Apply (.tpl)

Returns the character at a specified index in a valid string.

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Examples

Character at index 1▶ Try

INPUT

String: Hello
Index: 1

OUTPUT

e

First character▶ Try

INPUT

String: World
Index: 0

OUTPUT

W

Index out of bounds▶ Try

INPUT

String: Hello
Index: 10

OUTPUT

""

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GTM Configuration

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charAt

Read-Only Try Live

String

Returns the character at a specified index in a valid string.

*** Character at index 1***
Input: String: Hello
Index: 1
↪️ Output: e

*** First character***
Input: String: World
Index: 0
↪️ Output: W

*** Index out of bounds***
Input: String: Hello
Index: 10

Index

🔢 The index position of the character to retrieve.

Supported formats:
  ✓ Number

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 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]

Index number

🔗 Result Handling — Chain Variables

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

charAt()

+ Chain another variable

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Related Variables

Same category: String

→ assignParamsToString → concatenateValues → countWordsInString → endsWith → extract → extractFirstSegment → extractNumber → 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

/**
 * Returns the character at a specified index in a valid string.
 * 
 * @param {string} data.str - The string to retrieve the character from.
 * @param {number} data.idx - The index of the character to retrieve.
 * @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 input before processing.
 * 
 * @returns {string} The character at the specified index.
 *
 * @framework ggLowCodeGTMKit
 */
const charAt = function(input, index) {
    if (typeof input !== 'string' || index < 0 || index >= input.length) {
        return '';
    }
    return input.charAt(index);
};
const safeFunction = fn => typeof fn === 'function' ? fn : x => x;
const out = safeFunction(data.out);
// ===============================================================================
// charAt - Direct mode
// ===============================================================================
const applyCast = (castFn, value) => safeFunction(castFn)(value);
const processedStr = applyCast(data.pre, data.str);
return out(charAt(processedStr, data.idx));
// ===============================================================================
// charAt(...) – Apply Mode
// ===============================================================================
/*
return function(value, index) {
    index = data.rp1 ? data.idx : index;
    return out(charAt(value, index));
};
*/

🧪 View Test Scenarios (5 tests)

✅ '[example] Character at index 1'
✅ '[example] First character'
✅ Last character - should return last char
✅ '[example] Index out of bounds'
✅ Negative index - should return empty string