Avoid with Statement

ID

javascript.avoid_with

Severity

high

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Reliability

Language

JavaScript

Tags

best-practice, reliability

Description

Reports with(obj) { …​ }. The with statement is forbidden in strict mode, blocks engine optimisations such as compile-time variable resolution, and produces ambiguous identifier binding — readers can’t tell whether foo inside the block refers to a local variable or to obj.foo.

Rationale

  • Throws a SyntaxError in strict mode (which includes ES modules and class bodies by default).

  • Defeats minifiers and JIT optimisations: every identifier inside the body has to be resolved dynamically against the with object.

  • Hides typos — a misspelled property silently falls through to the outer scope, where it might match an unrelated variable.

// Bad - banned in strict mode, optimisation hostile
with (config) {
  enabled = true; // is this `config.enabled` or a free `enabled`?
}

Remediation

Use destructuring or a short alias instead.

// Good
const { enabled, threshold } = config;

// Or
const c = config;
c.enabled = true;

References