no-useless-escape - ESLint - Pluggable JavaScript Linter (original) (raw)
Disallow unnecessary escape characters
✅ Recommended
Using the recommended config from @eslint/js in a configuration file enables this rule
💡 hasSuggestions
Some problems reported by this rule are manually fixable by editor suggestions
Table of Contents
Escaping non-special characters in strings, template literals, and regular expressions doesn’t have any effect, as demonstrated in the following example:
let foo = "hol\a"; // > foo = "hola"
let bar = `${foo}\!`; // > bar = "hola!"
let baz = /\:/ // same functionality with /:/
Rule Details
This rule flags escapes that can be safely removed without changing behavior.
Examples of incorrect code for this rule:
/*eslint no-useless-escape: "error"*/
"\'";
'\"';
"\#";
"\e";
`\"`;
`\"${foo}\"`;
`\#{foo}`;
/\!/;
/\@/;
/[\[]/;
/[a-z\-]/;
Examples of correct code for this rule:
/*eslint no-useless-escape: "error"*/
"\"";
'\'';
"\x12";
"\u00a9";
"\371";
"xs\u2111";
`\``;
`\${${foo}}`;
`$\{${foo}}`;
/\\/g;
/\t/g;
/\w\$\*\^\./;
/[[]/;
/[\]]/;
/[a-z-]/;
Options
This rule has an object option:
allowRegexCharacters- An array of characters that should be allowed to have unnecessary escapes in regular expressions. This is useful for characters like-where escaping can prevent accidental character ranges. For example, in/[0\-]/, the escape is technically unnecessary but helps prevent the pattern from becoming a range if another character is added later (e.g.,/[0\-9]/vs/[0-9]/).
allowRegexCharacters
Examples of incorrect code for the { "allowRegexCharacters": ["-"] } option:
/*eslint no-useless-escape: ["error", { "allowRegexCharacters": ["-"] }]*/
/\!/;
/\@/;
/[a-z\^]/;
Examples of correct code for the { "allowRegexCharacters": ["-"] } option:
/*eslint no-useless-escape: ["error", { "allowRegexCharacters": ["-"] }]*/
/[0\-]/;
/[\-9]/;
/a\-b/;
When Not To Use It
If you don’t want to be notified about unnecessary escapes, you can safely disable this rule.
Version
This rule was introduced in ESLint v2.5.0.