How to Remove Extra Spaces, Trim & Clean String Formatting Issues Online

// Remove leading and trailing whitespace only
const cleaned = str.trim();
// "  hello world  " → "hello world"

// Also collapse multiple internal spaces to one
const cleaned = str.trim().replace(/s+/g, ' ');
// "  hello   world  " → "hello world"

// Remove ALL spaces (not recommended — loses word boundaries)
const noSpaces = str.replace(/s/g, '');
// "hello world" → "helloworld"

// Trim each line in a multiline string
const cleanedLines = str
  .split('
')
  .map(line => line.trim())
  .join('
');

// Remove blank lines too
const noBlankLines = str
  .split('
')
  .map(line => line.trim())
  .filter(line => line.length > 0)
  .join('
');

# Remove leading/trailing whitespace
cleaned = s.strip()
# "  hello   world  " → "hello   world"

# Trim and collapse internal spaces
import re
cleaned = re.sub(r's+', ' ', s).strip()
# "  hello   world  " → "hello world"

# Strip each line in a multiline string
lines = [line.strip() for line in s.splitlines()]
cleaned = '
'.join(line for line in lines if line)

// JavaScript
const lower = str.toLowerCase();     // "Hello World" → "hello world"
const upper = str.toUpperCase();     // "Hello World" → "HELLO WORLD"
const title = str.replace(/w/g, c => c.toUpperCase()); // Title Case

// Python
lower = s.lower()      # "Hello World" → "hello world"
upper = s.upper()      # "Hello World" → "HELLO WORLD"
title = s.title()      # "hello world" → "Hello World"
sentence = s.capitalize() # "hello world" → "Hello world"

// JavaScript — safe email comparison
const emailsMatch = userInput.toLowerCase() === storedEmail.toLowerCase();

// Python — safe string key lookup
if user_input.lower() == stored_value.lower():
    pass

// Replace all occurrences (use replaceAll or /g flag)
const result = str.replace(/old/g, 'new');        // All occurrences
const result = str.replaceAll('old', 'new');      // ES2021+

// Remove all digits
const noDigits = str.replace(/d/g, '');

// Remove all special characters (keep letters, numbers, spaces)
const clean = str.replace(/[^a-zA-Z0-9s]/g, '');

// Replace multiple spaces with single space
const collapsed = str.replace(/s+/g, ' ');

// Remove HTML tags
const noHtml = str.replace(/<[^>]*>/g, '');

// Replace line endings (normalize CRLF to LF)
const normalized = str.replace(/
/g, '
');

// Extract only the numbers from a string
const numbers = str.replace(/[^d.,-]/g, '');

// JavaScript split()
"a,b,c".split(",")           // → ["a", "b", "c"]
"hello world".split(" ")     // → ["hello", "world"]
"a  b  c".split(/s+/)       // → ["a", "b", "c"] (handles multiple spaces)
"abc".split("")              // → ["a", "b", "c"] (split into chars)

// Limit number of splits
"a,b,c,d".split(",", 2)      // → ["a", "b"] (first 2 only)

// Python split()
"a,b,c".split(",")           # → ["a", "b", "c"]
"a  b  c".split()            # → ["a", "b", "c"] (splits on any whitespace)
"a,b,c,d".split(",", 2)      # → ["a", "b", "c,d"] (max 2 splits)

// Split a JWT token
const [header, payload, signature] = jwtToken.split(".");
const decoded = JSON.parse(atob(payload));

// Remove all special chars — keep only letters, numbers, spaces
const clean = str.replace(/[^a-zA-Z0-9s]/g, '');

// Remove special chars — keep hyphens and underscores (for slugs/IDs)
const slug = str.replace(/[^a-zA-Z0-9-_]/g, '');

// Escape for use in a regex pattern (when user input becomes a regex)
const escaped = str.replace(/[.*+?^${}()|[]\]/g, '\$&');

// Escape HTML entities (prevent XSS)
const escapeHtml = (s) => s
  .replace(/&/g, '&')
  .replace(/</g, '&lt;')
  .replace(/>/g, '&gt;')
  .replace(/"/g, '&quot;')
  .replace(/'/g, '&#039;');

// Python — remove non-ASCII chars
import re
clean = re.sub(r'[^-]+', '', s)  # Remove non-ASCII

# Python — keep only alphanumeric
clean = re.sub(r'[^a-zA-Z0-9]', '', s)