noUndeclaredVariables (since v0.10.0)
Prevents the usage of variables that haven’t been declared inside the document
Examples
Invalid
foobar;
correctness/noUndeclaredVariables.js:1:1 lint/correctness/noUndeclaredVariables ━━━━━━━━━━━━━━━━━━━━
⚠ The foobar variable is undeclared
> 1 │ foobar;
│ ^^^^^^
2 │