falcon

Rules / Style / unnecessary-string-escapes

unnecessary-string-escapes

lint/style/unnecessary-string-escapes
recommended
Same as unnecessary_string_escapes · Dart lints

Flags a backslash escape that has no effect on the string's value.

A backslash only matters before a character that is special in the current string context: recognized escapes (\n, \t, \x, \u, and friends), the active quote character, $, and \ itself. Escaping anything else — \a, or \' inside a double-quoted string — produces the same character while adding visual clutter and inviting confusion about whether an escape was intended. Raw strings (r'...') are never analyzed since backslashes are literal there, and triple-quoted strings are skipped to avoid the edge cases around escaping runs of quotes. Remove the redundant backslash.

Invalid

example.dartdart
// Bad: backslash escapes that do nothing in the given string context.
void examples() {
  final a = "\'";
  final b = '\"';
  final c = '\a';
  final d = 'x\dy';
  final e = "50\%";
  final f = '\-';
  print([a, b, c, d, e, f]);
}
Unnecessary escape; the backslash can be removed.
2void examples() {
3 final a = "\'";
Unnecessary escape; the backslash can be removed.
3 final a = "\'";
4 final b = '\"';
Unnecessary escape; the backslash can be removed.
4 final b = '\"';
5 final c = '\a';
Unnecessary escape; the backslash can be removed.
5 final c = '\a';
6 final d = 'x\dy';
Unnecessary escape; the backslash can be removed.
6 final d = 'x\dy';
7 final e = "50\%";
Unnecessary escape; the backslash can be removed.
7 final e = "50\%";
8 final f = '\-';

Valid

example.dartdart
// Good: every backslash escape is meaningful (or the string is raw).
void examples() {
  final a = 'it\'s'; // escaping the delimiter quote is required
  final b = "she said \"hi\""; // escaping the delimiter quote is required
  final c = 'line1\nline2'; // \n is a newline
  final d = 'tab\there'; // \t is a tab
  final e = 'cost: \$5'; // \$ escapes interpolation
  final f = 'back\\slash'; // \\ is a literal backslash
  final g = r'\d+\w*'; // raw string — backslashes are literal, never flagged
  final h = 'emoji \u{1F600}'; // \u is a unicode escape
  final i = 'plain text';
  print([a, b, c, d, e, f, g, h, i]);
}

How to configure

Set the severity of unnecessary-string-escapes in your falcon.json:

falcon.jsonjson
{
  "linter": {
    "rules": {
      "style": {
        "unnecessary-string-escapes": "error"
      }
    }
  }
}

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