regexUnnecessaryDollarReplacements

Reports replacement string references to capturing groups that do not exist in the pattern.

✅ This rule is included in the ts logical and logicalStrict presets.

When using String.prototype.replace() or String.prototype.replaceAll() with a replacement string, referencing capturing groups that do not exist in the pattern is likely a mistake. This includes numeric references like $3 when only two groups exist, or named references like $<middle> when no such named group exists. These invalid references will be treated as literal text in the output, which is rarely the intended behavior.

This rule reports dollar replacements that are either invalid or unnecessary.

const 
const result: string
result = "ab".
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(/(a)(b)/, "$3");

const 
const result: string
result = "ab".
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(/a/, "$1");

const 
const result: string
result = "ab".
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(/(?<first>a)/, "$<middle>");

const 
const result: string
result = "ab".
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(/(a)(b)/, "$2$1");

const 
const result: string
result = "ab".
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(/(?<first>a)/, "$<first>");

const 
const result: string
result = "ab".
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(/a/, "$&");

const 
const result: string
result = "ab".
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(/a/, "$$1");

Options

This rule is not configurable.

When Not To Use It

If you intentionally use invalid dollar replacements as literal text (though this is rare and confusing), you might want to disable this rule. Consider escaping the dollar sign with $$ instead for clarity.

Equivalents in Other Linters

ESLint: regexp/no-useless-dollar-replacements

Made with ❤️‍🔥 around the world by the Flint team and contributors.

regexUnnecessaryDollarReplacements

Examples

Options

When Not To Use It

Further Reading

Equivalents in Other Linters