typescript eslint unsafe assignment of an any value

no-unsafe-assignment

Disallow assigning a value with type any to variables and properties.

Extending "plugin:@typescript-eslint/ recommended-type-checked " in an ESLint configuration enables this rule.

This rule requires type information to run.

The any type in TypeScript is a dangerous "escape hatch" from the type system. Using any disables many type checking rules and is generally best used only as a last resort or when prototyping code.

Despite your best intentions, the any type can sometimes leak into your codebase. Assigning an any typed value to a variable can be hard to pick up on, particularly if it leaks in from an external library.

This rule disallows assigning any to a variable, and assigning any[] to an array destructuring.

This rule also compares generic type argument types to ensure you don't pass an unsafe any in a generic position to a receiver that's expecting a specific type. For example, it will error if you assign Set<any> to a variable declared as Set<string> .

Try this rule in the playground ↗

• ❌ Incorrect

There are cases where the rule allows assignment of any to unknown .

Example of any to unknown assignment that are allowed:

This rule is not configurable.

When Not To Use It ​

If your codebase has many existing any s or areas of unsafe code, it may be difficult to enable this rule. It may be easier to skip the no-unsafe-* rules pending increasing type safety in unsafe areas of your project. You might consider using ESLint disable comments for those specific situations instead of completely disabling this rule.

Related To ​

• no-explicit-any
• no-unsafe-argument
• no-unsafe-call
• no-unsafe-member-access
• no-unsafe-return

Resources ​

• Rule source
• Test source
• When Not To Use It