20 lines
485 B
JavaScript
Executable file
20 lines
485 B
JavaScript
Executable file
function incrementListIndex(current, dir, opt) {
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const len = opt.choices.realLength;
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const shouldLoop = 'loop' in opt ? Boolean(opt.loop) : true;
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if (dir === 'up') {
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if (current > 0) {
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return current - 1;
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}
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return shouldLoop ? len - 1 : current;
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}
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if (dir === 'down') {
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if (current < len - 1) {
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return current + 1;
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}
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return shouldLoop ? 0 : current;
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}
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throw new Error('dir must be up or down');
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}
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module.exports = incrementListIndex;
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