Normalize input
Clean user-entered text before validation or storage.
JavaScript · Function
trim
trim() returns a new string with whitespace and line terminators removed from both ends of the string. It leaves the original string unchanged.
How it works
Call trim() on a string to create a new string with whitespace and line terminators removed from its beginning and end. The method does not mutate the original string; if no trimming is needed, it still returns a new string.
Syntax
trim()Returns
A new string representing the input string with whitespace removed from its beginning and end.
Key points
- trim() removes surrounding whitespace at both ends and produces a new string.
- Calling trim() does not change the string value on which it was called.
- Use trimStart() for the beginning only or trimEnd() for the end only.
- Its trimming set includes whitespace characters and line terminators.
- Even an already-trimmed string results in a separate returned string value.
Common mistakes
- The original string is not returned directly, even when it contains no surrounding whitespace.
- The method removes both whitespace characters and line terminators, not merely ordinary spaces.
Example: Trim both ends of a string
const raw = " hello, JavaScript!\n";
const clean = raw.trim();
console.log(clean); // "hello, JavaScript!"
console.log(raw); // " hello, JavaScript!\n"This removes whitespace at both ends while leaving the original string unchanged.
When to use it
Clean configuration values
Remove accidental surrounding whitespace from configuration or environment values.
Standardize text
Prepare text for reliable comparisons or display.
Related
String.prototype.trimStart()String.prototype.trimEnd()