typescript/no-base-to-string Correctness

✅ This rule is turned on by default.

🚧 An auto-fix is still under development.

What it does

This rule requires toString() and toLocaleString() calls to only be called on objects which provide useful information when stringified.

Why is this bad?

JavaScript's toString() method returns '[object Object]' on plain objects, which is not useful information. This rule prevents toString() and toLocaleString() from being called on objects that return less useful strings.

Examples

Examples of incorrect code for this rule:

// These will evaluate to '[object Object]'
({}).toString();
({ foo: "bar" }).toString();
({ foo: "bar" }).toLocaleString();

// This will evaluate to 'Symbol()'
Symbol("foo").toString();

Examples of correct code for this rule:

const someString = "Hello world";
someString.toString();

const someNumber = 42;
someNumber.toString();

const someBoolean = true;
someBoolean.toString();

class CustomToString {
  toString() {
    return "CustomToString";
  }
}
new CustomToString().toString();

How to use

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

CLI

oxlint --deny typescript/no-base-to-string

Config (.oxlintrc.json)

{
  "rules": {
    "typescript/no-base-to-string": "error"
  }
}

References

• Rule Source