// 概览
const myElement = document.getElementById('navigation');
const header = document.getElementsByTagName('header');
const elements = document.getElementsByClassName('anchorLocation');
const dwEles = document.getElementsByClassName('dw1');
const elementsArray = Array.from(elements);
const dwElesArray = Array.from(dwEles);

(function() {
    let activeKey = 0;
    window.addEventListener('scroll', function () {
        var scrollTop = window.pageYOffset || document.documentElement.scrollTop; // 获取页面滚动距离  
        if (scrollTop >= window.innerHeight * 0.75) {
            myElement.style.position = 'fixed'; // 如果子元素滑到最顶部，则设置为固定定位  
            myElement.style.top = '0';
            if(header[0]) {
                header[0]['style']['display'] = 'none';
            }
        } else {
            myElement.style.position = ''; // 否则，清空定位属性，使元素回到相对定位（默认值）  
            if(header[0]) {
                header[0]['style']['display'] = 'block';
            }
        }
        // 锚点定位高亮
        elementsArray.forEach((item, index) => {
            if (scrollTop + myElement.offsetHeight >= item.offsetTop) {
                activeKey = index;
            }
        });

        dwElesArray.forEach((ele,index) => {
            const a = ele.querySelector('a');
            if (index == activeKey) a.classList.add('navTitle');
            else a.classList.remove('navTitle');
        });
    });

}) ();
// 锚点定位
function anchorLocation(e,key) {
    const targetElement = elementsArray[key];
    targetElement.scrollIntoView({
        behavior: 'smooth',
        block: 'start' // Align to the top of the viewport
    });
}