typescript/no-misused-spread Correctness

✅ This rule is turned on by default when type-aware linting is enabled.

💭 This rule requires type information.

🚧 An auto-fix is planned for this rule, but not implemented at this time.

What it does

This rule disallows spreading syntax in places where it doesn't make sense or could cause runtime errors.

Why is this bad?

The spread operator can be misused in ways that might not be immediately obvious but can cause runtime errors or unexpected behavior. This rule helps catch common misuses.

Examples

Examples of incorrect code for this rule:

// Spreading a non-iterable value in an array
const num = 42;
const arr = [...num]; // Runtime error: num is not iterable

// Spreading a Promise in an array
const promise = Promise.resolve([1, 2, 3]);
const arr2 = [...promise]; // Runtime error: Promise is not iterable

// Spreading non-object in object literal
const str = "hello";
const obj = { ...str }; // Creates { '0': 'h', '1': 'e', ... } which might be unexpected

Examples of correct code for this rule:

// Spreading arrays
const arr1 = [1, 2, 3];
const arr2 = [...arr1];

// Spreading objects
const obj1 = { a: 1, b: 2 };
const obj2 = { ...obj1 };

// Spreading resolved Promise
const promise = Promise.resolve([1, 2, 3]);
const arr3 = [...(await promise)];

// Using Array.from for non-iterables if needed
const str = "hello";
const arr4 = Array.from(str); // ['h', 'e', 'l', 'l', 'o']

Configuration

This rule accepts a configuration object with the following properties:

allow

type: array

default: []

An array of type or value specifiers that are allowed to be spread even if they would normally be flagged as misused.

allow[n]

type: string

Type or value specifier for matching specific declarations

Supports four types of specifiers:

1. String specifier (deprecated): Universal match by name

"Promise"

2. File specifier: Match types/values declared in local files

{ "from": "file", "name": "MyType" }
{ "from": "file", "name": ["Type1", "Type2"] }
{ "from": "file", "name": "MyType", "path": "./types.ts" }

3. Lib specifier: Match TypeScript built-in lib types

{ "from": "lib", "name": "Promise" }
{ "from": "lib", "name": ["Promise", "PromiseLike"] }

4. Package specifier: Match types/values from npm packages

{ "from": "package", "name": "Observable", "package": "rxjs" }
{ "from": "package", "name": ["Observable", "Subject"], "package": "rxjs" }

How to use

To enable this rule using the config file or in the CLI, you can use:

Config (.oxlintrc.json)

{
  "rules": {
    "typescript/no-misused-spread": "error"
  }
}

CLI

oxlint --type-aware --deny typescript/no-misused-spread

References

• Rule Source
• Rule Source (tsgolint)