trimStart — GTM Variable Template for String

VARIABLES › STRING

trimStart CORE String

Direct (.tpl) Apply (.tpl)

Trims whitespace or specified characters from the start of a string, removing leading characters as specified.

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When to Use This

String Manipulation

Transform, clean, and normalize text data for consistent downstream processing.

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Examples

Trim custom leading characters▶ Try

INPUT

String To Trim: ###hello###
Characters To Remove: #

OUTPUT

hello###

No leading whitespace unchanged▶ Try

INPUT

String To Trim: hello world
Characters To Remove:

OUTPUT

hello world

Non-string returns empty string▶ Try

INPUT

String To Trim: 12345
Characters To Remove: undefined

OUTPUT

""

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GTM Configuration

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trimStart

Read-Only Try Live

String To Trim

💾 The string to trim from the start.

Supported formats:
  ✓ String

Trim Custom Character(s) (whitespace by default)

Characters To Remove

🔤 The characters to remove from the start (used when custom characters is enabled, default is whitespace). Each character is considered independently.

↳If characters like yi are specified, then both y and i will be removed from the start of the string, regardless of the order or frequency of occurrence.

Supported formats:
  ✓ String

Input Setup

Input Function (optional)

⚙️ Optional pre-processing function applied to the input before internal logic (e.g., normalize case, convert to string). Internal transformations such as string validation will still apply afterward.

Result Handling

Output Function (optional)

⚙️ Optional function to apply to the result before returning it (e.g., str => str.toUpperCase(), val => val + ' trimmed' for string modifications). Useful for chaining transformations on the output.

String To Trim 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]

Trim Custom Character(s) (whitespace by default)

Characters To Remove string

🔗 Result Handling — Chain Variables

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

trimStart()

+ Chain another variable

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Related Variables

Same category: String

→ assignParamsToString → charAt → 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 → truncate

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Under the Hood

📜 View Implementation Code

/**
* Trims whitespace or specified characters from the start of a string.
* 
* @param {string} data.src - The string to trim.
* @param {string} data.chr - The characters to remove (used when add is true, default is whitespace).
* @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 trimming.
* 
* @returns {string} The string with leading whitespace or specified characters removed.
*
* @framework ggLowCodeGTMKit
*/
const trimStart = function(string, chars) {
   const charsToTrim = chars !== undefined ? chars : " ";
   if (typeof string !== 'string') { return ""; }
   let startIndex = 0;
   while (startIndex < string.length && charsToTrim.indexOf(string.charAt(startIndex)) !== -1) {
       startIndex++;
   }
   return string.slice(startIndex);
};

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

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

// ===============================================================================
// trimStart() – Apply Mode
// ===============================================================================
/*
return function(value, chars) {
    chars = data.rp1 ? data.chr : chars;
  return out(trimStart(value, chars));
};
*/

🧪 View Test Scenarios (5 tests)

✅ Trim leading spaces
✅ '[example] Trim custom leading characters'
✅ '[example] No leading whitespace unchanged'
✅ String with leading tabs and newlines - should not remove them without custom chars usage
✅ '[example] Non-string returns empty string'