function $(className) {
    var newClassName = className.split(" ");
    if (newClassName.length > 1) {
        var father = newClassName[newClassName.length - 2];
        var childrenList = document.querySelector(father).children;

        var arr = Array.from(childrenList).filter(function (el) {
            if (
                el.className.indexOf((newClassName[newClassName.length - 1]).replace(".", "")) > -1
                ||
                el.tagName.toLowerCase() == newClassName[newClassName.length - 1]
            ) {
                return el;
            }
        });

        if (arr.length > 1) {
            return document.querySelectorAll(className)
        } else if (arr.length == 1) {
            return document.querySelector(className)
        } else {
            throw new Error(`${className} 不存在，请检查`)
        }

    } else {
        return document.querySelector(newClassName);

    }
}


// function scroll(callback) {
//     document.querySelector('bode').onscroll = () => {
//         let scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
//         let clientHeight = document.documentElement.clientHeight || document.body.clientHeight;
//         let scrollHeight = document.documentElement.scrollHeight || document.body.scrollHeight;

//         if (scrollHeight > clientHeight && scrollTop + clientHeight === scrollHeight) {
//             Array.from(b).filter((v, i) => {
//                 if (v.className.indexOf("active") > -1) {
//                     this.currentIndex = i;
//                 }
//             });

//             this.allUserDo[this.currentIndex].page += 1;
//             this.getdata("scroll");
//             console.log(this.currentIndex)
//         }
//     }
// }