获取屏幕内所有元素

此处演示只后去文本元素

function isElementInViewport(el) {
    var rect = el.getBoundingClientRect();
    return (
        rect.top >= 0 &&
        rect.left >= 0 &&
        rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) && /*or $(window).height() */
        rect.right <= (window.innerWidth || document.documentElement.clientWidth) /*or $(window).width() */
    );
};
var visibleEles = new Array();
function findVisibleElement(el, containerArray) {
    // console.log("type = " + Object.prototype.toString.call(el));
    var array = el.childNodes;
    if (array.length < 1 ) {
        // 去除不需要的 dom style
        if (Object.prototype.toString.call(el) === '[object Text]') {
            var parentnode = el.parentNode;
            if (Object.prototype.toString.call(parentnode) === '[object HTMLScriptElement]'
            ||
            Object.prototype.toString.call(parentnode) === '[object HTMLHeadElement]'
            ||
            Object.prototype.toString.call(parentnode) === '[object HTMLStyleElement]'
            ||
            Object.prototype.toString.call(parentnode) === '[object HTMLBodyElement]' 
            ) {
                return;
            }
            // 过滤空文本
            var content = parentnode.textContent;
            if (content == null || content.length <= 0) {
                // console.log('空字符串');
                return ;
            }
            console.log(parentnode.innerText);
            var iscontain = isElementInViewport(parentnode);
            // console.log(iscontain? "-- 内":"-- 外");       
            if (iscontain) {
                containerArray.push(content);
            }
        }
    } else {
        for (let index = 0; index < array.length; index++) {
            const element = array[index];
            this.findVisibleElement(element, containerArray);
        }
    }
}
findVisibleElement(document.documentElement, visibleEles);
visibleEles.join("");