Quite often you'll find the onload event firing way before the DOM has fully loaded, as many a Javascript developer can tell you. I'd summise from this that your iframe will have little, if any, effect on the onload event firing.
The biggest drawback is that they block the window onload event until complete, which can make the users perceive that the page they requested is slow. The do have their uses though in allowing you to compartmentalize external web pages or sandboxing another DOM structure outside of the main page.
My thoughts on this, Presuming you're talking about external sites , If we want alternate to Iframe , don't think there is one foolproof, If we go with CORS enabled AJAX web services , we still need some signature or some dependency for making sure the parameters are same.
Infact if we check SharePoint Apps , they are encouraging Iframe as it gives cleaner separation between2 apps to interact with one another. This is much more SEO friendly than iframe. The matter is: you have to try to deliver your assets in a way that is convenient to the end user, this is why you read or hear things like:.
So for iframes : if the iframe is provided by a third party, like Google or FB and that third party offers a async version, choose the async version. If that's not a choice, then you can tel the browser to wait for the important elements of the page to load, then after, add the iframe to your document with JS jQuery is your friend. Iframe affects page load time. Let me try to explain with a simple and easy example:.
You have a page and where you have2 iframes added on it which have2 different urls in them. Now this page will try to load3 pages in actual when you will try to open your page.
A few weeks ago I was at Heathrow airport getting a bit of work done before a flight, and I noticed something odd about the performance of GitHub: It was quicker to open links in a new window than simply click them.
Here's a video I took at the time:. Here I click a link, then paste the same link into a fresh tab. The page in the fresh tab renders way sooner, even though it's started later. This means the page can render progressively as it's downloading.
The page may be k, but it can render useful content after only 20k is received. This is a great, ancient browser feature, but as developers we often engineer it away. Most load-time performance advice boils down to "show them what you got" - don't hold back, don't wait until you have everything before showing the user anything.
GitHub cares about performance so they server-render their pages. However, when navigating within the same tab navigation is entirely reimplemented using JavaScript.
Something like…. This breaks the rule, as all of page-data. The server-rendered version doesn't hoard content this way, it streams, making it faster. For GitHub's client-side render, a lot of JavaScript was written to make this slow. I'm just using GitHub as an example here - this anti-pattern is used by almost every single-page-app.
When the onload event is delayed, it gives the user the perception that the page is slower. Browsers open a small number of connections to any given web server. This number has increased in newer browsers. You can see the complete table in my Roundup on Parallel Connections. In all major browsers, the connections are shared between the main page and its iframes. If the contents of the iframe are as important, or more important, than the main page, this is fine.
This is unfortunate, but understandable given the simplicity of using iframes for inserting content from an ad service. In many situations, iframes are the logical solution. But keep in mind the performance impact they can have on your page.
When possible, avoid iframes. When necessary, use them sparingly. Martin Borthiry Jun at am Permalink. I think that it is possible to solve the adsense problem.
Then, put a new script to set the SRC of the ads script, on the bottom page. Kirk Cerny Jun at pm Permalink. Danny Khatib Jun at pm Permalink. We have a similar problem where we render three ads on a page via Google Ad Manager, and have wrapped each partner ad code in iframes served from our domain to sandbox the code.
Steve Souders Jun at am Permalink. One concern I have is that many ad networks and other third-parties use the first js file as an entry point to download another js files and more content. If so, I suppose the middle ground would be to defer it for IE users and others soon. Thanks again!
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