link element onload

Question

Is there anyway to listen to the onload event for a element?

F.ex:

var link = document.createElement(\'link\');
link.rel =          


        

Answer 1

Since you didn't like my hack :) I looked around for some other way and found one by brothercake.

Basically, what is suggested is to get the CSS using AJAX to make the browser cache it and then treat the link load as instantaneous, since the CSS is cached. This will probably not work every single time (since some browsers may have cache turned off, for example), but almost always.

Answer 2

The xLazyLoader plugin fails since the cssRules properties are hidden for stylesheets that belong to other domains (breaks the same origin policy). So what you have to do is compare the ownerNode and owningElements.

Here is a thorough explanation of what todo: http://yearofmoo.com/2011/03/cross-browser-stylesheet-preloading/

Answer 3

This is a cross-browser solution

// Your css loader
var d = document,
    css = d.head.appendChild(d.createElement('link'))

css.rel = 'stylesheet';
css.type = 'text/css';
css.href = "https://unpkg.com/tachyons@4.10.0/css/tachyons.css"

// Add this  
if (typeof s.onload != 'undefined') s.onload = myFun;
} else {
    var img = d.createElement("img");
    img.onerror = function() {
      myFun();
      d.body.removeChild(img);
    }
    d.body.appendChild(img);
    img.src = src;
}

function myFun() {
    /* ..... PUT YOUR CODE HERE ..... */
}

The answer is based on this link that say:

What happens behind the scenes is that the browser tries to load the CSS in the img element and, because a stylesheet is not a type of image, the img element throws the onerror event and executes our function. Thankfully, browsers load the entire CSS file before determining its not an image and firing the onerror event.

In modern browsers you can do css.onload and add that code as a fallback to cover old browsers back to 2011 when only Opera and Internet Explorer supported the onload event and onreadystatechange respectively.

Note: I have answered here too and it is my duplicate and deserves to be punished for my honesteness :P

Answer 4

// this work in IE 10, 11 and Safari/Chrome/Firefox/Edge
// if you want to use Promise in an non-es6 browser, add an ES6 poly-fill (or rewrite to use a callback)

let fetchStyle = function(url) {
  return new Promise((resolve, reject) => {
    let link = document.createElement('link');
    link.type = 'text/css';
    link.rel = 'stylesheet';
    link.onload = resolve;
    link.href = url;

    let headScript = document.querySelector('script');
    headScript.parentNode.insertBefore(link, headScript);
  });
};

Answer 5

Another way to do this is to check how many style sheets are loaded. For instance:

With "css_filename" the url or filename of the css file, and "callback" a callback function when the css is loaded:

var style_sheets_count=document.styleSheets.length;
var css = document.createElement('link');
css.setAttribute('rel', 'stylesheet');
css.setAttribute('type', 'text/css');
css.setAttribute('href', css_filename);
document.getElementsByTagName('head').item(0).appendChild(css);
include_javascript_wait_for_css(style_sheets_count, callback, new Date().getTime());

function include_javascript_wait_for_css(style_sheets_count, callback, starttime)
/* Wait some time for a style sheet to load.  If the time expires or we succeed
 *  in loading it, call a callback function.
 * Enter: style_sheet_count: the original number of style sheets in the
 *                           document.  If this changes, we think we finished
 *                           loading the style sheet.
 *        callback: a function to call when we finish loading.
 *        starttime: epoch when we started.  Used for a timeout. 12/7/11-DWM */
{  
   var timeout = 10000; // 10 seconds
   if (document.styleSheets.length!=style_sheets_count || (new Date().getTime())-starttime>timeout)
      callback();
   else
      window.setTimeout(function(){include_javascript_wait_for_css(style_sheets_count, callback, starttime)}, 50);
}

Answer 6

E.g. Android browser doesn't support "onload" / "onreadystatechange" events for element: http://pieisgood.org/test/script-link-events/
But it returns:

"onload" in link === true

So, my solution is to detect Android browser from userAgent and then wait for some special css rule in your stylesheet (e.g., reset for "body" margins).
If it's not Android browser and it supports "onload" event- we will use it:

var userAgent = navigator.userAgent,
    iChromeBrowser = /CriOS|Chrome/.test(userAgent),
    isAndroidBrowser = /Mozilla\/5.0/.test(userAgent) && /Android/.test(userAgent) && /AppleWebKit/.test(userAgent) && !iChromeBrowser; 

addCssLink('PATH/NAME.css', function(){
    console.log('css is loaded');
});

function addCssLink(href, onload) {
    var css = document.createElement("link");
    css.setAttribute("rel", "stylesheet");
    css.setAttribute("type", "text/css");
    css.setAttribute("href", href);
    document.head.appendChild(css);
    if (onload) {
        if (isAndroidBrowser || !("onload" in css)) {
            waitForCss({
                success: onload
            });
        } else {
            css.onload = onload;
        }
    }
}

// We will check for css reset for "body" element- if success-> than css is loaded
function waitForCss(params) {
    var maxWaitTime = 1000,
        stepTime = 50,
        alreadyWaitedTime = 0;

    function nextStep() {
        var startTime = +new Date(),
            endTime;

        setTimeout(function () {
            endTime = +new Date();
            alreadyWaitedTime += (endTime - startTime);
            if (alreadyWaitedTime >= maxWaitTime) {
                params.fail && params.fail();
            } else {
                // check for style- if no- revoke timer
                if (window.getComputedStyle(document.body).marginTop === '0px') {
                    params.success();
                } else {
                    nextStep();
                }
            }
        }, stepTime);
    }

    nextStep();
}

Demo: http://codepen.io/malyw/pen/AuCtH