Simon Willison’s Weblog

Entries tagged javascript, ajax

Filters: Type: entry × javascript × ajax ×


How does a web page interact with a server to parse a dynamic JSON file?

If you’re only dealing with 60 records there’s no need to add a full database. I’ve actually hand coded a 50 record JSON file before and it was fine- use an editor with good JSON support (I like Sublime Text 2) and it’s pretty easy to hand write.

[... 103 words]

How do you change page content and URL without reloading the whole page?

This can only be done using JavaScript. You use XMLHttpRequest to pull in new information from the server (also known as Ajax—most people use a JavaScript library such as jQuery to handle this) and then use the HTML5 history API, in particular the pushState method, to update the URL.

[... 133 words]

Why do browsers allow cross-domain JavaScript to execute but not XMLHttpRequests?

It’s called the Same Origin Policy, and it’s principally about intranets. Imagine you have a URL http://intranet.corp/top-secret-...—and you then visit http://evil.example.com/ . If cross domain XHR was allowed the evil site could suck that secret document off your intranet without you realising.

[... 105 words]