unicorn/explicit-timer-delay

setTimeout(callback) runs the callback as soon as it can, as if the delay were 0. The reader can't tell whether that's on purpose or you forgot the delay. For setInterval() a forgotten delay means a callback that runs over and over without a pause. Writing 0 shows that you meant it.

The rule also checks the timers on window, globalThis, self and global.

--fix adds , 0. With "never", it removes the 0.

Configure

Off by default. To turn it on:

[lint.rules]
"unicorn/explicit-timer-delay" = "error" # or "warn"

Every option, set to its default:

[lint.rules]
"unicorn/explicit-timer-delay" = ["error", "always"] # "always" or "never"

Examples

Reported:

setTimeout(() => input.focus());

window.setInterval(poll);

Not reported:

setTimeout(() => input.focus(), 0);

window.setInterval(poll, 1000);

Options

Option	What it does
"always" (default)	Report a timer without a delay.
"never"	Report a delay of 0, which is the same as no delay. Other delays are fine.

setTimeout(() => input.focus(), 0);

setTimeout(() => input.focus());

setTimeout(() => input.blur(), 200);