variableDeletions

Reports attempting to delete variables with the delete operator.

✅ This rule is included in the ts untyped preset.

The delete operator is only meant to remove properties from objects, not variables. Attempting to delete a variable in strict mode will cause a syntax error. In non-strict mode, it will silently fail and return false without actually deleting the variable, which can lead to confusing bugs.

Examples

❌ Incorrect

let count = 5;
delete count;

function calculate(value: number) {
  delete value;
}

✅ Correct

let count = 5;
count = undefined;

const obj = { property: 1 };
delete obj.property;

Options

This rule is not configurable.

When Not To Use It

This rule should always be enabled, as attempting to delete variables is always incorrect behavior in JavaScript and TypeScript.

Further Reading

• MDN documentation on the delete operator
• MDN JavaScript Reference: Strict mode

Equivalents in Other Linters

• Deno: no-delete-var
• ESLint: no-delete-var
• Oxlint: eslint/no-delete-var