Javascript 加载事件监听器

Question

I just wanted to ask how do you ensure that element details (eg position in viewport, getBoundingClientRect) are correct when loading your page for the first time. Currently I have a problem with a normal div-element. It is displayed right after an image which i get with a fetch statement. I used the load-event on window and after the Page is loaded I get the information of the position of the div-element. Unfortunately the load-fires before the Image is loaded and that means the position details are wrong. How and when do you use the load Event? And what Else can i do to ensure i receive the right position details.

Html <div class="wrapperImg"></div> <div class="position"></div>

Js window.addEventListener("load",()=>{console.log(document.querySelector(".position").getBoundingClientRect());}

Many thanks Regards Kat

Answer 1

You'd need to call the getBoundingClientRect() after the image has loaded, which means when your fetch call has resolved (as it is executed asynchronously).

To keep in mind: The load event does not include asnyc fetched resources (as those are handled dynamically). For more info on the load event see the documentation .

Answer 2

'load' event listener can also be applied on images like this:

 var img = new Image(); img.src = "img.jpg"; img.onload = function () { alert("image is loaded"); }

Also you can get getBoundingClientRect() properties after the fetch:

 fetch('image.png').then(i => { //get size })