javascript - Javascript fixed-top navbar only after scrolling

Question

Does anyone know what javascript effects are being used to create the navbar effect on lesscss.org where the navbar only becomes fixed to the top after scrolling beyond a certain point. If anyone has actual code examples, or links to tutorials, that'd be appreciated.

Answer 1

这是使用window.onscroll事件的 javascript 检查

在顶部附近的 HTML 源代码中：

window.onscroll = function () {
    if (!docked && (menu.offsetTop - scrollTop() < 0)) {
      menu.style.top = 0;
      menu.style.position = 'fixed';
      menu.className = 'docked';
      docked = true;
    } else if (docked && scrollTop() <= init) {
      menu.style.position = 'absolute';
      menu.style.top = init + 'px';
      menu.className = menu.className.replace('docked', '');
      docked = false;
    }
};