Vue Js Check if element top of window:In Vue.js, you can dynamically check if an element has hit the top of the window using a combination of the window object and Vue’s reactive data properties. First, you can use the mounted() lifecycle hook to attach an event listener to the scroll event of the window object. Then, inside the event listener, you can use the getBoundingClientRect() method to get the position of the element relative to the viewport, and compare it to the window.pageYOffset property, which gives the current scroll position. By updating a reactive data property based on this comparison, you can trigger any necessary actions or updates in your component.

How can I dynamically check if an element in Vue.js has hit the top of the window as the user scrolls?

This Vue.js code dynamically checks if an element hits the top of the window when the user scrolls the page.

The HTML code contains a div element with an id of app and a child div element with a ref attribute set to test. There is also a small element with a class of result that will display the result if the item has reached the top of the window.

The Vue.js code starts by creating an app instance using the Vue.createApp method. The data function returns an object that contains a result property initialized to an empty string.

The mounted lifecycle hook is used to add an event listener to the window object that listens for the scroll event. When the user scrolls the page, the scrollTop value is compared to the offsetTop value of the test element. If the scrollTop value is greater than or equal to the offsetTop value, the result property is set to the string “Item has reached the top”. Otherwise, the result property is set back to an empty string.

Vue Js Dynamically Check If Element Hit Top Of Window Example

<div id="app">
    <div ref="test">Vue Js Dynamically check if elements hit top of window</div>
    <small class="result" v-if="result">{{result}}</small>
 </div>
    <script type="module">
        const app = Vue.createApp({
            data() {
                return {
                    result: ''
                };
            },
            mounted() {
                const itemOffset = this.$refs.test.offsetTop;

                window.addEventListener('scroll', () => {
                    const scrollTop = window.scrollY;
                    if (scrollTop >= itemOffset) {
                        this.result = 'Item has reached the top';
                    }
                    else {
                        this.result = ''
                    }
                });
            },
        })app.mount('#app')
 </script>

Output of Vue Js Check if Element hit top of window