regexDollarEscapes

Reports replacement strings with unescaped $ that should use $$.

✅ This rule is included in the ts stylistic and stylisticStrict presets.

Enforces escaping the $ character as $$ when using it literally in the replacement argument of String.prototype.replace() and String.prototype.replaceAll().

In these methods, $ has special meaning for substitution patterns like $& (matched substring), $1 (first capture group), etc. An unescaped $ followed by an unrecognized character will be treated as a literal $, but this behavior is confusing and error-prone.

This rule reports unescaped $ characters in replacement strings that are not valid substitution pattern matchers.

Examples

const 
const result: string
result = "€100".
String.replace(searchValue: {
    [Symbol.replace](string: string, replaceValue: string): string;
}, replaceValue: string): string (+3 overloads)
Passes a string and
{@linkcode
replaceValue
}
to the [Symbol.replace] method on
{@linkcode
searchValue
}
. This method is expected to implement its own replacement algorithm.
@param ― searchValue An object that supports searching for and replacing matches within a string.
@param ― replaceValue The replacement text.
replace(/€/, "$");

const 
const result: string
result = "€100".
String.replace(searchValue: {
    [Symbol.replace](string: string, replaceValue: string): string;
}, replaceValue: string): string (+3 overloads)
Passes a string and
{@linkcode
replaceValue
}
to the [Symbol.replace] method on
{@linkcode
searchValue
}
. This method is expected to implement its own replacement algorithm.
@param ― searchValue An object that supports searching for and replacing matches within a string.
@param ― replaceValue The replacement text.
replace(/€/, "$$");

Dollar Before Invalid Substitution Character

❌ Incorrect
✅ Correct

const 
const result: string
result = "abc".
String.replace(searchValue: {
    [Symbol.replace](string: string, replaceValue: string): string;
}, replaceValue: string): string (+3 overloads)
Passes a string and
{@linkcode
replaceValue
}
to the [Symbol.replace] method on
{@linkcode
searchValue
}
. This method is expected to implement its own replacement algorithm.
@param ― searchValue An object that supports searching for and replacing matches within a string.
@param ― replaceValue The replacement text.
replace(/./, "$x");

const 
const result: string
result = "abc".
String.replace(searchValue: {
    [Symbol.replace](string: string, replaceValue: string): string;
}, replaceValue: string): string (+3 overloads)
Passes a string and
{@linkcode
replaceValue
}
to the [Symbol.replace] method on
{@linkcode
searchValue
}
. This method is expected to implement its own replacement algorithm.
@param ― searchValue An object that supports searching for and replacing matches within a string.
@param ― replaceValue The replacement text.
replace(/./, "$$x");

Valid Substitution Patterns

✅ Correct

const 
const matchedSubstring: string
matchedSubstring = "abc".
String.replace(searchValue: {
    [Symbol.replace](string: string, replaceValue: string): string;
}, replaceValue: string): string (+3 overloads)
Passes a string and
{@linkcode
replaceValue
}
to the [Symbol.replace] method on
{@linkcode
searchValue
}
. This method is expected to implement its own replacement algorithm.
@param ― searchValue An object that supports searching for and replacing matches within a string.
@param ― replaceValue The replacement text.
replace(/./, "$&");
const 
const firstGroup: string
firstGroup = "abc".
String.replace(searchValue: {
    [Symbol.replace](string: string, replaceValue: string): string;
}, replaceValue: string): string (+3 overloads)
Passes a string and
{@linkcode
replaceValue
}
to the [Symbol.replace] method on
{@linkcode
searchValue
}
. This method is expected to implement its own replacement algorithm.
@param ― searchValue An object that supports searching for and replacing matches within a string.
@param ― replaceValue The replacement text.
replace(/(.)/, "$1");
const 
const namedGroup: string
namedGroup = "abc".
String.replace(searchValue: {
    [Symbol.replace](string: string, replaceValue: string): string;
}, replaceValue: string): string (+3 overloads)
Passes a string and
{@linkcode
replaceValue
}
to the [Symbol.replace] method on
{@linkcode
searchValue
}
. This method is expected to implement its own replacement algorithm.
@param ― searchValue An object that supports searching for and replacing matches within a string.
@param ― replaceValue The replacement text.
replace(/(?<char>.)/, "$<char>");
const 
const literalDollar: string
literalDollar = "abc".
String.replace(searchValue: {
    [Symbol.replace](string: string, replaceValue: string): string;
}, replaceValue: string): string (+3 overloads)
Passes a string and
{@linkcode
replaceValue
}
to the [Symbol.replace] method on
{@linkcode
searchValue
}
. This method is expected to implement its own replacement algorithm.
@param ― searchValue An object that supports searching for and replacing matches within a string.
@param ― replaceValue The replacement text.
replace(/./, "$$");

Options

This rule is not configurable.

When Not To Use It

If you intentionally rely on the behavior where $ followed by an unrecognized character produces a literal $, you might prefer to disable this rule.

Equivalents in Other Linters

ESLint: regexp/prefer-escape-replacement-dollar-char

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