@fruits-chain/react-native-xiaoshu/lib/module/picker-view/helper/column.js

🌈 React Native UI library

/**
 * 按照某个方向找到可用选项的下标
 */
const findAvailableOptionsIndex = (options, start, end) => {
  const isNext = end - start >= 0;

  for (let iii = start; isNext ? iii <= end : iii >= end; iii += isNext ? 1 : -1) {
    const item = options[iii];

    if (!item.disabled) {
      return iii;
    }
  }

  return -1;
};

export const findUsableOptionIndex = function (options, next, index) {
  let reverse = arguments.length > 3 && arguments[3] !== undefined ? arguments[3] : true;
  const maxIndex = options.length - 1; // 两端的情况不能反转查找

  if (reverse && (index === 0 || index === maxIndex)) {
    reverse = false;
  } // 顶端不能继续向上找


  if (index === 0 && !next) {
    next = true;
  } // 末端不能继续向下找


  if (index === maxIndex && next) {
    next = false;
  }

  const getEnd = cNext => {
    return cNext ? maxIndex : 0;
  }; // 以当前为起点向某个方向找


  let nIndex = findAvailableOptionsIndex(options, index, getEnd(next));

  if (nIndex === -1 && reverse) {
    nIndex = findAvailableOptionsIndex(options, index, getEnd(!next));
  }

  return nIndex;
};
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