no-restricted-syntax

Sometimes you want to ban one piece of the language in your project and there's no rule for it, like for..in loops, TypeScript enums, or a call to one function with one kind of argument. This rule takes a list of selectors and reports every syntax tree node that matches one.

A selector names an ESTree node type, such as ForInStatement, and can narrow it down the way a CSS selector does: by attribute ([name="eval"]), by parent (A > B), by ancestor (A B), or with :not(), :is() and :has(). TypeScript syntax uses typescript-eslint's node types, such as TSEnumDeclaration.

The rule does nothing until you give it a selector.

Configure#

Off by default. To turn it on:

[lint.rules]
"no-restricted-syntax" = "error" # or "warn"

Examples#

[lint.rules]
"no-restricted-syntax" = ["error", "ForInStatement"]

for (const key in settings) {
  apply(key, settings[key]);
}

for (const key of Object.keys(settings)) {
  apply(key, settings[key]);
}

Options#

Each option is a selector, or an object with a selector and the message to show.

This selector matches a literal, such as a string, that's the first argument of setTimeout:

[lint.rules]
"no-restricted-syntax" = ["error", {
  selector = "CallExpression[callee.name='setTimeout'] > Literal:first-child",
  message = "Pass a function to setTimeout.",
}]

setTimeout("refresh()", 1000);

setTimeout(refresh, 1000);

In a TypeScript file:

enum Color {
  Red,
  Blue,
}

type Color = "red" | "blue";