Make position: fixed behavior like sticky (for Vue2) - css

Question

Position: sticky doesn't support by the most mobile browsers. But position: fixed is not that thing I need (because of fixed block overlaps content in the bottom of document).
I guess for jquery it will be easy to set static position for fixed block if we get bottom of document onscroll.
But for Vue2 I haven't any idea how to do the same. Give some advice please. Or maybe better solution exists.

Answer 1

As I mentioned in the comments, I'd recommend using a polyfill if at all possible. They will have put a lot of effort into getting it right. However, here is a simple take on how you might do it in Vue.
I have the application handle scroll events by putting the scrollY value into a data item. My sticky-top component calculates what its fixed top position would be, and if it's > 0, it uses it. The widget is position: relative.
new Vue({
el: '#app',
data: {
scrollY: null
},
mounted() {
window.addEventListener('scroll', (event) => {
this.scrollY = Math.round(window.scrollY);
});
},
components: {
stickyTop: {
template: '<div class="a-box" :style="myStyle"></div>',
props: ['top', 'scrollY'],
data() {
return {
myStyle: {},
originalTop: 0
}
},
mounted() {
this.originalTop = this.$el.getBoundingClientRect().top;
},
watch: {
scrollY(newValue) {
const rect = this.$el.getBoundingClientRect();
const newTop = this.scrollY + +this.top - this.originalTop;
if (newTop > 0) {
this.$set(this.myStyle, 'top', `${newTop}px`);
} else {
this.$delete(this.myStyle, 'top');
}
}
}
}
}
});
#app {
height: 1200px;
}
.spacer {
height: 80px;
}
.a-box {
display: inline-block;
height: 5rem;
width: 5rem;
border: 2px solid blue;
position: relative;
}
<script src="//unpkg.com/vue#latest/dist/vue.js"></script>
<div id="app">
<div class="spacer"></div>
<div class="a-box"></div>
<sticky-top top="20" :scroll-y="scrollY"></sticky-top>
<div class="a-box"></div>
</div>

Answer 2

This seem to work for me
...
<header
ref="header"
class="header-container"
:class="{ 'header-container--sticky': isHeaderSticky }"
>
...
...
data() {
return{
scrollY: null,
headerTop: 0,
isHeaderSticky: false,
}
},
mounted() {
window.addEventListener('load', () => {
window.addEventListener('scroll', () => {
this.scrollY = Math.round(window.scrollY);
});
this.headerTop = this.$refs.header.getBoundingClientRect().top;
});
},
watch: {
scrollY(newValue) {
if (newValue > this.headerTop) {
this.isHeaderSticky = true;
} else {
this.isHeaderSticky = false;
}
}
}
...
...
.header-container {
&--sticky {
position: sticky;
top: 0;
z-index: 9999;
}
}
...