@rbxts/jsnatives

trimStart

Removes whitespace from the beginning of a string.

Signature

function trimStart(str: string): string

Description

The trimStart function removes whitespace characters from the beginning of a string, and returns a new string. Whitespace includes spaces, tabs, newlines, and other whitespace characters.

Parameters

str: The string to trim.

Return value

A new string with whitespace removed from the beginning.

Examples

Basic usage

// Remove whitespace from the beginning
const trimmed = String.trimStart("  Hello world  ");
print(trimmed); // Outputs: "Hello world  "

// Trim tabs and newlines
const multiline = String.trimStart("\t\n Hello \n\t");
print(multiline); // Outputs: "Hello \n\t"

Chaining with other string operations

// Trim start and then convert to uppercase
const text = "  hello world  ";
const processedText = String.toUpperCase(String.trimStart(text));
print(processedText); // Outputs: "HELLO WORLD  "

Handling empty strings

// Trimming an empty string
const empty = String.trimStart("");
print(empty); // Outputs: "" (empty string)

// Trimming a string with only whitespace
const onlyWhitespace = String.trimStart("   \t\n  ");
print(onlyWhitespace); // Outputs: "" (empty string)

Practical applications

// Format code indentation
function removeLeadingIndentation(code: string): string {
  const lines = String.split(code, "\n");
  const trimmedLines = [];

  for (const line of lines) {
    trimmedLines.push(String.trimStart(line));
  }

  return trimmedLines.join("\n");
}

const code = "    function hello() {\n        print('Hello');\n    }";
const formatted = removeLeadingIndentation(code);
print(formatted);
// Outputs:
// function hello() {
// print('Hello');
// }

Comparison with trim and trimEnd

const text = "  Hello world  ";

// Using trimStart
const startOnly = String.trimStart(text);
print(startOnly); // Outputs: "Hello world  "

// Using trim
const bothEnds = String.trim(text);
print(bothEnds); // Outputs: "Hello world"

// Using trimEnd
const endOnly = String.trimEnd(text);
print(endOnly); // Outputs: "  Hello world"