Dynamically load css stylesheet and wait for it to load

Question

I have a script that detects a button click on which it will attach a CSS stylesheet to the "head" with jQuery like so:

const link = "<link class='listcss' rel='stylesheet' href='http://....list.css'>";
$("head").append(link);

Then I need to do some calculations based on the css width and height properties:

function CSSDone(){
            if($(window).width()>640){
                $(".grid-item").css({"height":$(".grid-item").width()*0.2});
                $(".grid_item_img").css({"height":$(".grid-item").width()*0.2});
            console.log("a");
            }else{
                $(".grid-item").css({"height":$(".grid-item").width()*0.33});
                $(".grid_item_img").css({"height":$(".grid-item").width()*0.33});
            console.log("b");       
            }
        }
        CSSDone();

However, if I launch CSSDone(); right after adding the stylesheet, the calculations happen before the css is loaded. I searched the web like crazy but everything I tried doesn't work:

I tried these options:

1. Does not work:

   link.onload = function () { CSSDone(); }

2. Does not work:

    if (link.addEventListener) {
      link.addEventListener('load', function() {
        CSSDone();
      }, false);
    }
   

3. Does not work:

    link.onreadystatechange = function() {
      var state = link.readyState;
      if (state === 'loaded' || state === 'complete') {
        link.onreadystatechange = null;
        CSSDone();
      }
    };
   

4. Does not work:

    $(window).load(function () {
        CSSDone();
    });
   

5. Does not work:

    $(window).bind("load", function() {
        CSSDone();
    });
   

Believe me. Nothing works......

---

**One workaround:**

I load the css in the DOM and immidiately remove it again with jQuery. That way when adding the link to the head later it's fast enough.

Answer 1

You need to insert a link node in the head and then attach onload event to that. In your code link is a String. See sample code below on how to implement what you want.

var link = document.createElement('link');
link.setAttribute("rel", "stylesheet");
link.setAttribute("type", "text/css");
link.onload = CSSDone;
link.setAttribute("href", 'https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css');
document.getElementsByTagName("head")[0].appendChild(link);

Check jsfiddle.

MDN reference on Link element in case you are curious

Answer 2

You can try this i believe.. include the CSSDone() code in $("head").append(link)'s callback

$(document).ready(function(){
$('.btn').on('click', function(){
link = "<link class='listcss' rel='stylesheet' href='/list.css'>";
        $("head").append(link, function(){
        if($(window).width()>640){
                $(".grid-item").css({"height":$(".grid-item").width()*0.2});
                $(".grid_item_img").css({"height":$(".grid-item").width()*0.2});
            console.log("a");
            }else{
                $(".grid-item").css({"height":$(".grid-item").width()*0.33});
                $(".grid_item_img").css({"height":$(".grid-item").width()*0.33});
            console.log("b");       
            }

        }); // append link

        }); // button click
}); // document ready

Answer 3

Using jQuery:

var head = $('head');
var link = $('<link>')
    .attr('rel', 'stylesheet')
    .attr('type', 'text/css')
    .attr('href', url)
                        .on('load', callback)
                        .on('error', error)
                       .appendTo(head);