18 lines
462 B
Plaintext
18 lines
462 B
Plaintext
export default function incrementListIndex(current, dir, opt) {
|
|
const len = opt.choices.realLength;
|
|
const shouldLoop = 'loop' in opt ? Boolean(opt.loop) : true;
|
|
if (dir === 'up') {
|
|
if (current > 0) {
|
|
return current - 1;
|
|
}
|
|
return shouldLoop ? len - 1 : current;
|
|
}
|
|
if (dir === 'down') {
|
|
if (current < len - 1) {
|
|
return current + 1;
|
|
}
|
|
return shouldLoop ? 0 : current;
|
|
}
|
|
throw new Error('dir must be up or down');
|
|
}
|