mounted() {
// let _this=this
window.addEventListener('scroll', () => {
let top = document.documentElement.scrollTop || document.body.scrollTop || window.pageYOffset
console.log(top);
if (top > 700) {
this.scrollTag = true;
} else {
this.scrollTag = false
}
})
}

来源:https://blog.csdn.net/qq_42074075/article/details/99736565