String trim( )

Returns the string without any leading and trailing whitespace.

If the string contains leading or trailing whitespace, a new string with no leading and no trailing whitespace is returned:

'\tDart is fun\n'.trim(); // 'Dart is fun'

Otherwise, the original string itself is returned:

var str1 = 'Dart';
var str2 = str1.trim();
identical(str1, str2);    // true

Whitespace is defined by the Unicode White_Space property (as defined in version 6.2 or later) and the BOM character, 0xFEFF.

Here is the list of trimmed characters (following version 6.2):

0009..000D    ; White_Space # Cc   <control-0009>..<control-000D>
0020          ; White_Space # Zs   SPACE
0085          ; White_Space # Cc   <control-0085>
00A0          ; White_Space # Zs   NO-BREAK SPACE
1680          ; White_Space # Zs   OGHAM SPACE MARK
180E          ; White_Space # Zs   MONGOLIAN VOWEL SEPARATOR
2000..200A    ; White_Space # Zs   EN QUAD..HAIR SPACE
2028          ; White_Space # Zl   LINE SEPARATOR
2029          ; White_Space # Zp   PARAGRAPH SEPARATOR
202F          ; White_Space # Zs   NARROW NO-BREAK SPACE
205F          ; White_Space # Zs   MEDIUM MATHEMATICAL SPACE
3000          ; White_Space # Zs   IDEOGRAPHIC SPACE

FEFF          ; BOM                ZERO WIDTH NO_BREAK SPACE

Source

/**
 * Returns the string without any leading and trailing whitespace.
 *
 * If the string contains leading or trailing whitespace, a new string with no
 * leading and no trailing whitespace is returned:
 *
 *     '\tDart is fun\n'.trim(); // 'Dart is fun'
 *
 * Otherwise, the original string itself is returned:
 *
 *     var str1 = 'Dart';
 *     var str2 = str1.trim();
 *     identical(str1, str2);    // true
 *
 * Whitespace is defined by the Unicode White_Space property (as defined in
 * version 6.2 or later) and the BOM character, 0xFEFF.
 *
 * Here is the list of trimmed characters (following version 6.2):
 *
 *     0009..000D    ; White_Space # Cc   <control-0009>..<control-000D>
 *     0020          ; White_Space # Zs   SPACE
 *     0085          ; White_Space # Cc   <control-0085>
 *     00A0          ; White_Space # Zs   NO-BREAK SPACE
 *     1680          ; White_Space # Zs   OGHAM SPACE MARK
 *     180E          ; White_Space # Zs   MONGOLIAN VOWEL SEPARATOR
 *     2000..200A    ; White_Space # Zs   EN QUAD..HAIR SPACE
 *     2028          ; White_Space # Zl   LINE SEPARATOR
 *     2029          ; White_Space # Zp   PARAGRAPH SEPARATOR
 *     202F          ; White_Space # Zs   NARROW NO-BREAK SPACE
 *     205F          ; White_Space # Zs   MEDIUM MATHEMATICAL SPACE
 *     3000          ; White_Space # Zs   IDEOGRAPHIC SPACE
 *
 *     FEFF          ; BOM                ZERO WIDTH NO_BREAK SPACE
 */
String trim();