Using
$("a").attr("href", "http://www.google.com/")
will modify the href of all hyperlinks to point to Google. You probably want a somewhat more refined selector though. For instance, if you have a mix of link source (hyperlink) and link target (a.k.a. "anchor") anchor tags:
<a name="MyLinks"></a>
<a href="http://www.codeproject.com/">The CodeProject</a>
...Then you probably don't want to accidentally add href attributes to them. For safety then, we can specify that our selector will only match <a> tags with an existing href attribute:
$("a[href]") //...
Of course, you'll probably have something more interesting in mind. If you want to match an anchor with a specific existing href, you might use something like this:
$("a[href='http://www.google.com/']").attr('href', 'http://www.live.com/')
This will find links where the href exactly matches the string http://www.google.com/. A more involved task might be matching, then updating only part of the href:
$("a[href^='http://stackoverflow.com']")
.each(function()
{
this.href = this.href.replace(/^http:\/\/beta\.stackoverflow\.com/,
"http://stackoverflow.com");
});
The first part selects only links where the href starts with http://stackoverflow.com. Then, a function is defined that uses a simple regular expression to replace this part of the URL with a new one. Note the flexibility this gives you - any sort of modification to the link could be done here.
Most of the jQuery Ajax methods return an XMLHttpRequest (or the equivalent) object, so you can just use abort().
See the documentation:
- abort Method (MSDN). Cancels the current HTTP request.
- abort() (MDN). If the request has been sent already, this method will abort the request.
var xhr = $.ajax({
type: "POST",
url: "some.php",
data: "name=John&location=Boston",
success: function(msg){
alert( "Data Saved: " + msg );
}
});
//kill the request
xhr.abort()
UPDATE:
As of jQuery 1.5 the returned object is a wrapper for the native XMLHttpRequest object called jqXHR. This object appears to expose all of the native properties and methods so the above example still works. See The jqXHR Object (jQuery API documentation).
UPDATE 2:
As of jQuery 3, the ajax method now returns a promise with extra methods (like abort), so the above code still works, though the object being returned is not an xhr any more. See the 3.0 blog here.
UPDATE 3: xhr.abort() still works on jQuery 3.x. Don't assume the update 2 is correct. More info on jQuery Github repository.
Best Answer
This is a copy from my answers in a very similar question: How to check file input size with jQuery?
You actually don't have access to the filesystem (for example reading and writing local files). However, due to the HTML5 File API specification, there are some file properties that you do have access to, and the file size is one of them.
For this HTML:
try the following:
As it is a part of the HTML5 specification, it will only work for modern browsers (v10 required for IE) and I added here more details and links about other file information you should know: http://felipe.sabino.me/javascript/2012/01/30/javascipt-checking-the-file-size/
Old browsers support
Be aware that old browsers will return a
nullvalue for the previousthis.filescall, so accessingthis.files[0]will raise an exception and you should check for File API support before using it