@antmjs/vantui/lib/virtual-list/utils.js

一套适用于Taro3及React的vantui组件库

"use strict";

var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.getClosestIndex = getClosestIndex;
var _defineProperty2 = _interopRequireDefault(require("@babel/runtime/helpers/defineProperty"));
function ownKeys(object, enumerableOnly) { var keys = Object.keys(object); if (Object.getOwnPropertySymbols) { var symbols = Object.getOwnPropertySymbols(object); enumerableOnly && (symbols = symbols.filter(function (sym) { return Object.getOwnPropertyDescriptor(object, sym).enumerable; })), keys.push.apply(keys, symbols); } return keys; }
function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { var source = null != arguments[i] ? arguments[i] : {}; i % 2 ? ownKeys(Object(source), !0).forEach(function (key) { (0, _defineProperty2.default)(target, key, source[key]); }) : Object.getOwnPropertyDescriptors ? Object.defineProperties(target, Object.getOwnPropertyDescriptors(source)) : ownKeys(Object(source)).forEach(function (key) { Object.defineProperty(target, key, Object.getOwnPropertyDescriptor(source, key)); }); } return target; }
function getClosestIndex(rects, scrollTop) {
  var rectsArr = [];
  for (var key in rects) {
    var rect = rects[key];
    rectsArr.push(_objectSpread(_objectSpread({}, rect), {}, {
      index: Number(key)
    }));
  }
  var start = 0;
  var end = rectsArr.length - 1;
  var resIndex = undefined;
  while (start <= end) {
    var midIndex = Math.floor((start + end) / 2);
    var midValue = rectsArr[midIndex].top;
    if (midValue === scrollTop) {
      return rectsArr[midIndex].index;
    }
    if (midValue < scrollTop) {
      if (resIndex === undefined || resIndex < midIndex) {
        resIndex = midIndex;
      }
      start = midIndex + 1;
    }
    if (midValue > scrollTop) {
      end = midIndex - 1;
    }
  }
  resIndex = resIndex || 0;
  return rectsArr[resIndex].index;
}