UseVar [anti-pattern] v0.1.0

Using var to declare any binding in modern JavaScript or TypeScript. var is hoisted to the enclosing function, has no temporal-dead-zone protection, and is silently re-declarable — three properties that exist only because var predates block scoping.

Label

Declaring variables with var

Why Bad

var leaks across blocks. A var i inside an if is visible at the top of the function and after the block exits. Re-declaring the same var is silent. Hoisting means the binding exists before its declaration line, which surprises readers and breaks closures inside loops. Every modern style guide and lint configuration treats var as legacy noise.

Instead Do

    Use `const` for bindings you do not reassign and `let` for bindings
    you do. Both are block-scoped, neither is hoisted past the start of
    the block, and both throw on duplicate declaration. Turn on the
    ESLint `no-var` rule as `error` to catch regressions.
  

UseVar [anti-pattern] v0.1.0

Using var to declare any binding in modern JavaScript or TypeScript. var is hoisted to the enclosing function, has no temporal-dead-zone protection, and is silently re-declarable — three properties that exist only because var predates block scoping.

Label

Declaring variables with var

Why Bad

var leaks across blocks. A var i inside an if is visible at the top of the function and after the block exits. Re-declaring the same var is silent. Hoisting means the binding exists before its declaration line, which surprises readers and breaks closures inside loops. Every modern style guide and lint configuration treats var as legacy noise.

Instead Do

    Use `const` for bindings you do not reassign and `let` for bindings
    you do. Both are block-scoped, neither is hoisted past the start of
    the block, and both throw on duplicate declaration. Turn on the
    ESLint `no-var` rule as `error` to catch regressions.
  

Label

Declaring variables with var

Why Bad

var leaks across blocks. A var i inside an if is visible at the top of the function and after the block exits. Re-declaring the same var is silent. Hoisting means the binding exists before its declaration line, which surprises readers and breaks closures inside loops. Every modern style guide and lint configuration treats var as legacy noise.

Instead Do

    Use `const` for bindings you do not reassign and `let` for bindings
    you do. Both are block-scoped, neither is hoisted past the start of
    the block, and both throw on duplicate declaration. Turn on the
    ESLint `no-var` rule as `error` to catch regressions.