vant/lib/utils/scroll.js

A Vue.js 2.0 Mobile UI at YouZan

'use strict';

exports.__esModule = true;

var _index = require('./index');

exports.default = {
  debounce: function debounce(func, wait, immediate) {
    var timeout = void 0,
        args = void 0,
        context = void 0,
        timestamp = void 0,
        result = void 0;
    return function () {
      context = this;
      args = arguments;
      timestamp = new Date();
      var later = function later() {
        var last = new Date() - timestamp;
        if (last < wait) {
          timeout = setTimeout(later, wait - last);
        } else {
          timeout = null;
          result = func.apply(context, args);
        }
      };
      if (!timeout) {
        timeout = setTimeout(later, wait);
      }
      return result;
    };
  },


  /* 找到最近的触发滚动事件的元素
   * @param {Element} element
  * @param {Element} rootElement
  * @return {Element | window}
   */
  getScrollEventTarget: function getScrollEventTarget(element) {
    var rootParent = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : window;

    var currentNode = element;
    // bugfix, see http://w3help.org/zh-cn/causes/SD9013 and http://stackoverflow.com/questions/17016740/onscroll-function-is-not-working-for-chrome
    while (currentNode && currentNode.tagName !== 'HTML' && currentNode.tagName !== 'BODY' && currentNode.nodeType === 1 && currentNode !== rootParent) {
      var overflowY = this.getComputedStyle(currentNode).overflowY;
      if (overflowY === 'scroll' || overflowY === 'auto') {
        return currentNode;
      }
      currentNode = currentNode.parentNode;
    }
    return rootParent;
  },


  // 判断元素是否被加入到页面节点内
  isAttached: function isAttached(element) {
    var currentNode = element.parentNode;
    while (currentNode) {
      if (currentNode.tagName === 'HTML') {
        return true;
      }
      if (currentNode.nodeType === 11) {
        return false;
      }
      currentNode = currentNode.parentNode;
    }
    return false;
  },


  // 获取滚动高度
  getScrollTop: function getScrollTop(element) {
    return 'scrollTop' in element ? element.scrollTop : element.pageYOffset;
  },


  // 设置滚动高度
  setScrollTop: function setScrollTop(element, value) {
    'scrollTop' in element ? element.scrollTop = value : element.scrollTo(element.scrollX, value);
  },


  // 获取元素距离顶部高度
  getElementTop: function getElementTop(element) {
    return (element === window ? 0 : element.getBoundingClientRect().top) + this.getScrollTop(window);
  },
  getVisibleHeight: function getVisibleHeight(element) {
    return element === window ? element.innerHeight : element.getBoundingClientRect().height;
  },


  getComputedStyle: !_index.isServer && document.defaultView.getComputedStyle.bind(document.defaultView)
};