It seems like jQuery is the industry standard for integrating ajax into websites. I like to be able to look at code and understand how it does what it does though. What is in jQuery? Isn't it basically javascript? How can I learn how to write my own javascript code to do what jQuery does in the instances that I want to use it for such as uploading images without refreshing the page? When I search for ajax tutorials they all just tell me to use jQuery.
>>1
1. Have /prog/ laugh at you
2. Get jQuery library (http://jquery.com/)
3. Read source code
4. Plagiarize
5. ...
6. PROFIT
7. Have /prog/ laugh at you
Name:
Anonymous2010-05-20 15:26
I don't want to use what someone else has already done because I want to know how to do everything myself. jQuery is where the magic happens and I want to learn how to be a magician.
Also to answer your questions, yes, it is basically Javascript. The special thing about jQuery is that you don't have to worry about browser compatibility etc.
They are right to tell you to use jQuery, to keep you from the horrors of writing your own XmlHttpRequest nonsense (since each browser implements it differently)!
This is why JS development is exploding recently: we've never had a framework like jQuery/dojo/mootools/yahoo/protoype to standardize things--and make it necessary to write much, much less code to do simple things across all common browsers.
Besides Javascript being the wrong place to start, this attitude will get you absolutely nothing
Name:
Anonymous2010-05-20 15:33
It seems like only a small part of the jQuery file applies to what I am actually trying to do with a particular part of the website functionality. So why do I need to reference the whole file if I could just use part of the code? What part of the ajax performance does jQuery specifically facilitate?
if ( s.cache === false && type === "GET" ) {
var ts = now();
// try replacing _= if it is there
var ret = s.url.replace(rts, "$1_=" + ts + "$2");
// if nothing was replaced, add timestamp to the end
s.url = ret + ((ret === s.url) ? (rquery.test(s.url) ? "&" : "?") + "_=" + ts : "");
}
// If data is available, append data to url for get requests
if ( s.data && type === "GET" ) {
s.url += (rquery.test(s.url) ? "&" : "?") + s.data;
}
// Watch for a new set of requests
if ( s.global && ! jQuery.active++ ) {
jQuery.event.trigger( "ajaxStart" );
}
// Matches an absolute URL, and saves the domain
var parts = rurl.exec( s.url ),
remote = parts && (parts[1] && parts[1] !== location.protocol || parts[2] !== location.host);
// If we're requesting a remote document
// and trying to load JSON or Script with a GET
if ( s.dataType === "script" && type === "GET" && remote ) {
var head = document.getElementsByTagName("head")[0] || document.documentElement;
var script = document.createElement("script");
script.src = s.url;
if ( s.scriptCharset ) {
script.charset = s.scriptCharset;
}
// Handle Script loading
if ( !jsonp ) {
var done = false;
// Handle memory leak in IE
script.onload = script.onreadystatechange = null;
if ( head && script.parentNode ) {
head.removeChild( script );
}
}
};
}
// Use insertBefore instead of appendChild to circumvent an IE6 bug.
// This arises when a base node is used (#2709 and #4378).
head.insertBefore( script, head.firstChild );
// We handle everything using the script element injection
return undefined;
}
var requestDone = false;
// Create the request object
var xhr = s.xhr();
if ( !xhr ) {
return;
}
// Open the socket
// Passing null username, generates a login popup on Opera (#2865)
if ( s.username ) {
xhr.open(type, s.url, s.async, s.username, s.password);
} else {
xhr.open(type, s.url, s.async);
}
// Need an extra try/catch for cross domain requests in Firefox 3
try {
// Set the correct header, if data is being sent
if ( s.data || origSettings && origSettings.contentType ) {
xhr.setRequestHeader("Content-Type", s.contentType);
}
// Set the If-Modified-Since and/or If-None-Match header, if in ifModified mode.
if ( s.ifModified ) {
if ( jQuery.lastModified[s.url] ) {
xhr.setRequestHeader("If-Modified-Since", jQuery.lastModified[s.url]);
}
if ( jQuery.etag[s.url] ) {
xhr.setRequestHeader("If-None-Match", jQuery.etag[s.url]);
}
}
// Set header so the called script knows that it's an XMLHttpRequest
// Only send the header if it's not a remote XHR
if ( !remote ) {
xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
}
// Set the Accepts header for the server, depending on the dataType
xhr.setRequestHeader("Accept", s.dataType && s.accepts[ s.dataType ] ?
s.accepts[ s.dataType ] + ", */*" :
s.accepts._default );
} catch(e) {}
// Allow custom headers/mimetypes and early abort
if ( s.beforeSend && s.beforeSend.call(callbackContext, xhr, s) === false ) {
// Handle the global AJAX counter
if ( s.global && ! --jQuery.active ) {
jQuery.event.trigger( "ajaxStop" );
}
// close opended socket
xhr.abort();
return false;
}
if ( s.global ) {
trigger("ajaxSend", [xhr, s]);
}
// Wait for a response to come back
var onreadystatechange = xhr.onreadystatechange = function( isTimeout ) {
// The request was aborted
if ( !xhr || xhr.readyState === 0 || isTimeout === "abort" ) {
// Opera doesn't call onreadystatechange before this point
// so we simulate the call
if ( !requestDone ) {
complete();
}
// The transfer is complete and the data is available, or the request timed out
} else if ( !requestDone && xhr && (xhr.readyState === 4 || isTimeout === "timeout") ) {
requestDone = true;
xhr.onreadystatechange = jQuery.noop;
if ( status === "success" ) {
// Watch for, and catch, XML document parse errors
try {
// process the data (runs the xml through httpData regardless of callback)
data = jQuery.httpData( xhr, s.dataType, s );
} catch(err) {
status = "parsererror";
errMsg = err;
}
}
// Make sure that the request was successful or notmodified
if ( status === "success" || status === "notmodified" ) {
// JSONP handles its own success callback
if ( !jsonp ) {
success();
}
} else {
jQuery.handleError(s, xhr, status, errMsg);
}
// Override the abort handler, if we can (IE doesn't allow it, but that's OK)
// Opera doesn't fire onreadystatechange at all on abort
try {
var oldAbort = xhr.abort;
xhr.abort = function() {
if ( xhr ) {
oldAbort.call( xhr );
}
onreadystatechange( "abort" );
};
} catch(e) { }
// Timeout checker
if ( s.async && s.timeout > 0 ) {
setTimeout(function() {
// Check to see if the request is still happening
if ( xhr && !requestDone ) {
onreadystatechange( "timeout" );
}
}, s.timeout);
}
// Send the data
try {
xhr.send( type === "POST" || type === "PUT" || type === "DELETE" ? s.data : null );
} catch(e) {
jQuery.handleError(s, xhr, null, e);
// Fire the complete handlers
complete();
}
// firefox 1.5 doesn't fire statechange for sync requests
if ( !s.async ) {
onreadystatechange();
}
function success() {
// If a local callback was specified, fire it and pass it the data
if ( s.success ) {
s.success.call( callbackContext, data, status, xhr );
}
// Fire the global callback
if ( s.global ) {
trigger( "ajaxSuccess", [xhr, s] );
}
}
function complete() {
// Process result
if ( s.complete ) {
s.complete.call( callbackContext, xhr, status);
}
// The request was completed
if ( s.global ) {
trigger( "ajaxComplete", [xhr, s] );
}
// Handle the global AJAX counter
if ( s.global && ! --jQuery.active ) {
jQuery.event.trigger( "ajaxStop" );
}
}
>>6
Nothing wrong with that attitude, but one must learn wether knowing implementation details for a specific thing is worth their time or not, for we are but human and don't have the time to learn every system ever concieved.
>>12
I had an employer like that once. That attitude eventually caused every competent programmer there to quit and form their own programming shop, leaving him with the two guys who loved Java and the ``graphic designer''. They went under a month later.
The world's not all bad, kids.
>>14
Are you posting messages on this board from work? A guy can take a little time to ask some questions can't he?
So jQuery covers the essentials for getting my code to work right in different browsers but doesn't really have much to do with the javascript that I write to get my ajax functionality to work properly?
Name:
Anonymous2010-05-21 8:53
Rewrite a jQuery-ish library in Lisp and make it compile to native javascript. You kill both your problems.
Otherwise use dojo instead of jQuery, since you can just import the modules you want.