react-bootstrap/src/AffixMixin.js

Bootstrap 3 components build with React

import React from 'react';
import domUtils from './utils/domUtils';
import EventListener from './utils/EventListener';

const AffixMixin = {
  propTypes: {
    offset: React.PropTypes.number,
    offsetTop: React.PropTypes.number,
    offsetBottom: React.PropTypes.number
  },

  getInitialState() {
    return {
      affixClass: 'affix-top'
    };
  },

  getPinnedOffset(DOMNode) {
    if (this.pinnedOffset) {
      return this.pinnedOffset;
    }

    DOMNode.className = DOMNode.className.replace(/affix-top|affix-bottom|affix/, '');
    DOMNode.className += DOMNode.className.length ? ' affix' : 'affix';

    this.pinnedOffset = domUtils.getOffset(DOMNode).top - window.pageYOffset;

    return this.pinnedOffset;
  },

  checkPosition() {
    let DOMNode, scrollHeight, scrollTop, position, offsetTop, offsetBottom,
        affix, affixType, affixPositionTop;

    // TODO: or not visible
    if (!this.isMounted()) {
      return;
    }

    DOMNode = React.findDOMNode(this);
    scrollHeight = document.documentElement.offsetHeight;
    scrollTop = window.pageYOffset;
    position = domUtils.getOffset(DOMNode);

    if (this.affixed === 'top') {
      position.top += scrollTop;
    }

    offsetTop = this.props.offsetTop != null ?
      this.props.offsetTop : this.props.offset;
    offsetBottom = this.props.offsetBottom != null ?
      this.props.offsetBottom : this.props.offset;

    if (offsetTop == null && offsetBottom == null) {
      return;
    }
    if (offsetTop == null) {
      offsetTop = 0;
    }
    if (offsetBottom == null) {
      offsetBottom = 0;
    }

    if (this.unpin != null && (scrollTop + this.unpin <= position.top)) {
      affix = false;
    } else if (offsetBottom != null && (position.top + DOMNode.offsetHeight >= scrollHeight - offsetBottom)) {
      affix = 'bottom';
    } else if (offsetTop != null && (scrollTop <= offsetTop)) {
      affix = 'top';
    } else {
      affix = false;
    }

    if (this.affixed === affix) {
      return;
    }

    if (this.unpin != null) {
      DOMNode.style.top = '';
    }

    affixType = 'affix' + (affix ? '-' + affix : '');

    this.affixed = affix;
    this.unpin = affix === 'bottom' ?
      this.getPinnedOffset(DOMNode) : null;

    if (affix === 'bottom') {
      DOMNode.className = DOMNode.className.replace(/affix-top|affix-bottom|affix/, 'affix-bottom');
      affixPositionTop = scrollHeight - offsetBottom - DOMNode.offsetHeight - domUtils.getOffset(DOMNode).top;
    }

    this.setState({
      affixClass: affixType,
      affixPositionTop
    });
  },

  checkPositionWithEventLoop() {
    setTimeout(this.checkPosition, 0);
  },

  componentDidMount() {
    this._onWindowScrollListener =
      EventListener.listen(window, 'scroll', this.checkPosition);
    this._onDocumentClickListener =
      EventListener.listen(domUtils.ownerDocument(this), 'click', this.checkPositionWithEventLoop);
  },

  componentWillUnmount() {
    if (this._onWindowScrollListener) {
      this._onWindowScrollListener.remove();
    }

    if (this._onDocumentClickListener) {
      this._onDocumentClickListener.remove();
    }
  },

  componentDidUpdate(prevProps, prevState) {
    if (prevState.affixClass === this.state.affixClass) {
      this.checkPositionWithEventLoop();
    }
  }
};

export default AffixMixin;