quick-lint-js

Find bugs in JavaScript programs.

E0098: for loop needs an iterable, or condition and update clauses

There are three kinds of for loops: C-style for loops (;), for-in loops, and for-of loops. It is a syntax error to write a for loop without ;, in, or of:

for (const enemy) {
  enemy.health -= damage;
}

for (let i) {
  console.log(i % 15 ? i : "FizzBuzz");
}

To fix this error, write in or of followed by an iterable (such as an array):

for (const enemy of collidedEntities) {
  enemy.health -= damage;
}

Alternatively, write the remainder of the C-style for loop:

for (let i = 0; i < 100; ++i) {
  console.log(i % 15 ? i : "FizzBuzz");
}

Documentation for other errors