Hi I've been trying to clarify this but there's something I'm still confused about. I know that you can't return values from asynchronous functions so I've referenced this answer's top answer Returning value from asynchronous JavaScript method?
What I'm trying to do is use the flickrAPI to get the biggest size image. The flickrAPI allows one to search images, so I use this to get the photo_id, then I use this photo_id to procses another request to the API's getSize method to get the URL for the biggest size photo.
The code looks a little messy as it is, because I have a method called flickrRequest which sends an XMLHttp request and gets back a JSON string. I know that I can achieve what I want by writing the functions as follows:
function flickRQforimage() {
...got ID
function flickrRQforSize() {
...got maxsizeURL
create image based on maxsizeURL here
}
}
but I was wondering if it was possible to do something like this
function flickRQforimage() {
...got ID
function flickrRQforSize() {
...got maxsizeURL
}
create image based on maxsizeURL here
}
or even create image based on maxsizeURL here
In general my question is whether it is possible to have a callback function that references another statically defined function (I think?). The specifics of the my function is that it takes a callback and the ID and URL processing happens in those callbacks:
flickrRQ(options, cb)
I am wondering whether/what would happen if that unnamed function is instead something else, say flickrRQ(options, processPhoto(data)), and then I define the function in a separate method. This just makes sense for me because I want to keep functionality for the URL processing separate in an attempt to make my code cleaner and more readable.
I tried the following below and it didn't work. Nothing prints. I even have a console.log in the processPhoto method. In fact anything inside of the flickrRQforSize method seems to not evaluate
flickrRQforSize(options, function(data) {
processPhoto(data)
}
even though in the flickrRQforSize definition, a callback function is taken as an argument. I'm suspecting there must be something about functions/async calls that I don't understand.
I hope this is clear -- if not, I can post my actual code.
Here's my code:
var flickrRequest = function(options, xhrRQ, cb) {
var url, xhr, item, first;
url = "https://api.flickr.com/services/rest/";
first = true;
for (item in options) {
if (options.hasOwnProperty(item)) {
url += (first ? "?" : "&") + item + "=" + options[item];
//parses to search equest;
first = false;
}
}
//XMLHttpRQ to flickr
if(xhrRQ == 1 ) {
xhr = new XMLHttpRequest();
xhr.onload = function() { cb(this.response); };
xhr.open('get', url, true);
xhr.send();
};
}
var processPhotoSize = function(photoJSON) {
var parsedJSON = JSON.parse(data);
var last = parsedJSON.sizes.size.length;
console.log(parsedJSON.sizes.size[last-1].source);
return parsedJSON.sizes.size[last-1].source;
}
...
flickrRequest(options, 1, function(data) {
...
flickrRequest(sizesOptions, 0, function(data) {
parsedJSON = JSON.parse(data);
console.log(parsedJSON);
processPhotoSize(data);
});
}
Related
Here i am trying to open the file in new tab by calling ViewFile action of Doctor controller using Ajax Success which is in functionabc(this) on click of anchor tag.
Now the problem is that everything is as required but the url doesnot open in new tab.
Below is my Ajax
<script>
function abc(thisEvent) {
debugger;
var getDoCredId = $(thisEvent).attr('docCredId');
var parameter = { id: getDoCredId };
$.ajax({
url: "/Doctor/ViewFile1",
type: "get",
dataType: "html",
data: parameter,
success: function (data) {
debugger;
if (data = true) {
debugger;
var getdoctorId = $(thisEvent).attr('docCredId');
var url = "/Doctor/ViewFile/" + getdoctorId;
window.open(url, "_blank");
}
else {
debugger;
showNotification("Error", "warning");
}
}
});
}
Below is my anchor tag HTML
<a title="View Attachment" docCredId = "' + getDocCredId + '" onclick="abc(this)"><i class="btn btn-web-tbl btn-warning fa fa-eye "></i></a>
Below is code behind
public bool ViewFile1(int id)
{
var document = _doctorService.GetDoctorCredentialDetails(id);
string AttachPath = ConfigPath.DoctorCredentialsAttachmentPath;
string strFileFullPath = Path.Combine(AttachPath, document.AttachedFile);
string contentType = MimeTypes.GetMimeType(strFileFullPath);
bool checkFileInFolder = System.IO.File.Exists(strFileFullPath);
if (checkFileInFolder == true)
{
return true;
}
else
{
return false;
}
}
public ActionResult ViewFile(int id)
{
var document = _doctorService.GetDoctorCredentialDetails(id);
string AttachPath = ConfigPath.DoctorCredentialsAttachmentPath;
string strFileFullPath = Path.Combine(AttachPath, document.AttachedFile);
string contentType = MimeTypes.GetMimeType(strFileFullPath);
bool checkFileInFolder = System.IO.File.Exists(strFileFullPath);
bool filedata = System.IO.File.ReadAllBytes(strFileFullPath).Any();
byte[] filedata1 = System.IO.File.ReadAllBytes(strFileFullPath);
var cd = new System.Net.Mime.ContentDisposition
{
FileName = document.FileName,
Inline = true
};
Request.HttpContext.Response.Headers.Add("Content-Disposition", cd.ToString());
return File(filedata1, contentType);
}
Since this is too long for a regular comment, I am posting this as an answer, although it isn't directly going solve the problem because I am not able to reproduce it, but might give some insights and let you check the differences with what happens in your code as compared with this simplified example.
Calling window.open() from jQuery ajax success callback works just fine: https://codepen.io/nomaed/pen/dgezRa
I used the same pattern as you did, without your server code but using jsonplaceholder.typicode.com sample API instead.
There are some issues with the code sample that you might want to consider, even though you didn't ask for comments about it and it's not directly related to your issue (probably):
if (data = true) means data will always be true. You probably mean to do a if (data === true) if you know it's a boolean value, or if (data) if you want to accept any truthy value (true, {}, "something", 42, etc). Judging by the Java code and how you define the response format in the jQuery ajax call, it looks like you're expecting the "data" variable result be an HTML and not a boolean. You might want to try and remove the dataType: "html" row and let jQuery set the data format according to what is coming back from the server, and/or send a JSON formatted response, as in a POJO of { result: true } for a successful response. Then make sure that data.result === true to be sure that you got what you expect.
You should probably add arbitrary data to tags DOM elements the data-* attributes and if you're using jQuery, access them using the .data() selector. White adding just random attributs with string values may work, it's considered an abuse of the HTML and DOM, and the data-* attributes are there specifically for adding any data.
In the abc() function you grab the value of the attribute in the beginning (var getDoCredId = $(thisEvent).attr('docCredId');) but in the callback you're trying to get the value once more. You really don't need it since the success() callback is a closure in the scope of the abc() function and it has access to the value already, so doing var getdoctorId = $(thisEvent).attr('docCredId'); in the callback is really not needed.
I'd also suggest naming getDoCredId variable just as docCredId. Having a "get" prefix usually means that it's a getter function or a reference to some getter. Likewise, the "thisEvent" argument of the main function should probably be called "callerElement" or something like that since it's not an event, it's an actual element that you're passing directly from the DOM when calling abc(this) in the onClick event handler of the <a> anchor. This is just to make the code clearer to understand for anyone who's reading it, and for yourself when you're coming back to it several months in the future and trying to figure out what's going on :)
Try adding async: false to your Ajax request
function abc(thisEvent) {
debugger;
var getDoCredId = $(thisEvent).attr('docCredId');
var parameter = { id: getDoCredId };
$.ajax({
async: false, // <<<----------- add this
url: "/Doctor/ViewFile1",
type: "get",
dataType: "html",
data: parameter,
success: function (data) {
debugger;
if (data = true) {
debugger;
var getdoctorId = $(thisEvent).attr('docCredId');
var url = "/Doctor/ViewFile/" + getdoctorId;
window.open(url, "_blank");
}
else {
debugger;
showNotification("Error", "warning");
}
}
});
}
I have function like that
function cryptChange(cr){
var url = 'https://min-api.cryptocompare.com/data/dayAvg?fsym=' + cr + '&tsym=PLN';
console.log(url); // it's just for testing in console
};
cryptChange('LTC');
cryptChange('BTC');
As you can see this code is working fine with URL of AJAX call with JSON data, returning valid URL.
Want to make something like that, but in shorter version,
I have many lines of code like the ones below and I do want to get less
$.getJSON('https://min-api.cryptocompare.com/data/dayAvg?fsym=BTC&tsym=PLN', function(btc2){
$('#tt-11').html(btc2.PLN.toFixed(2)); //its passed into html block
});
$.getJSON('https://min-api.cryptocompare.com/data/dayAvg?fsym=BCH&tsym=PLN', function(bch2){
$('#tt-12').html(bch2.PLN.toFixed(2));
});
And now I want to mix that cryptChange function with AJAX call to pass parameter for callback and use that in $ ('#tt-11').html (btc2 here <==.PLN.toFixed (2);
Is that clearer guys now?
Define a function that takes all the varying parts as parameters.
function getCrypt(from, to, id) {
$.getJSON('https://min-api.cryptocompare.com/data/dayAvg', {
fsym: from,
tsym: to
}, function(result){
$('#' + id).html(result[to].toFixed(2));
});
You can then do:
getCrypt('BTC', 'PLN', 'tt-11');
getCrypt('BCH', 'PLN', 'tt-12');
I just implemented ag-grid, but found that IE9 crashes when using cellTemplates with angular compiled templates inside.
Did any of you encounter this and maybe found a workaround?
How to reproduce:
Head here (http://www.ag-grid.com/angular-grid-cell-template/index.php) with IE, and from DevTools, select IE9.
It will crash because of the angular compiled templates. Not sure what I can do about it.
(I also opened an issue on GitHub on this: https://github.com/ceolter/ag-grid/issues/521 )
EDIT:
Debugged it, there's an infinite loop because an update to an array from one method, is not visible to another method somehow...
The infinite loop is:
getTemplate, (wait in line until the call ends), call ends, template added to cache, run callback, callback doesn't see the template in templateCache, creates another callback, adds it to the queue, and so on.
(code from ag-grid below).
// returns the template if it is loaded, or null if it is not loaded
// but will call the callback when it is loaded
TemplateService.prototype.getTemplate = function (url, callback) {
var templateFromCache = this.templateCache[url];
if (templateFromCache) {
return templateFromCache;
}
var callbackList = this.waitingCallbacks[url];
var that = this;
if (!callbackList) {
// first time this was called, so need a new list for callbacks
callbackList = [];
this.waitingCallbacks[url] = callbackList;
// and also need to do the http request
var client = new XMLHttpRequest();
client.onload = function () {
that.handleHttpResult(this, url);
};
client.open("GET", url);
client.send();
}
// add this callback
if (callback) {
callbackList.push(callback);
}
// caller needs to wait for template to load, so return null
return null;
};
TemplateService.prototype.handleHttpResult = function (httpResult, url) {
if (httpResult.status !== 200 || httpResult.response === null) {
console.warn('Unable to get template error ' + httpResult.status + ' - ' + url);
return;
}
// response success, so process it
this.templateCache[url] = httpResult.response;
// inform all listeners that this is now in the cache
var callbacks = this.waitingCallbacks[url];
for (var i = 0; i < callbacks.length; i++) {
var callback = callbacks[i];
// we could pass the callback the response, however we know the client of this code
// is the cell renderer, and it passes the 'cellRefresh' method in as the callback
// which doesn't take any parameters.
callback();
}
if (this.$scope) {
var that = this;
setTimeout(function () {
that.$scope.$apply();
}, 0);
}
};
return TemplateService;
})();
I eventually found the issue.
In IE9, the template is on responseText inside the response.
In IE10+ and all other browsers it's on response.
So in order to fix it, in the above code, instead of:
// response success, so process it
this.templateCache[url] = httpResult.response;
I added:
// response success, so process it
//in IE9 the response is in - responseText
this.templateCache[url] = httpResult.response || httpResult.responseText;
For future reference, adding the answer here.
Had nothing to do with Angular. :)
UPDATE:
https://github.com/ceolter/ag-grid/issues/521
Code got into the repo :)
Thanks Niall Crosby (ceolter).
I am just trying FB JS api and want to know whether or how I can still use "response" out of FB.api. For example:
var picture;
FB.api('/me/picture?width=180&height=180', function (response) {
picture = response.data.url;
console.log(picture);
});
alert(picture);
The above code will show "undefined" in alert window.
Is there a way to use "response.data.url" out of FB.api?
Thanks
Update:
Here is the big picture: I need retrieve some information from FB user account, such as /me/name, /me/address/city, /me/picture.data.url and group them together and then send the information to server through AJAX.
var name;
var city;
var picture;
FB.api('/me', function (response) {
name = response.name;
FB.api('/me/address', function (adrresponse) {
city = adrresponse.city;
}
FB.api('/me/picture', function (imgresponse) {
picture = imgresponse.data.url;
}
//since FB API is async, the following is not correct!!!
var params = "name="+name+"&city="+city+"&picture="+picture;
//send out through AJAX.
var http = new XMLHttpRequest();
http.open("POST", url, true);
}
Is there a better way to finish the above job?
Update 2:
The best way is to use fields expansion
https://developers.facebook.com/docs/graph-api/using-graph-api/v2.3#fieldexpansion, as shown by the answer of this question.
Thanks
Derek
The problem is the picture variable is not populated at the time that the alert fires. It will only be populated after the FB.api callback completes.
var picture;
FB.api('/me/picture?width=180&height=180', function (response) {
picture = response.data.url;
// this would work correctly
alert(picture);
});
What are you attempting to do with the picture variable? Perhaps you should call a function do something with the picture inside your callback:
var picture;
FB.api('/me/picture?width=180&height=180', function (response) {
picture = response.data.url;
doSomethingWithPicture(picture);
});
Update
The simple way to achieve what you are after is this:
FB.api('/me', function (response) {
var name = response.name;
FB.api('/me/address', function (adrresponse) {
var city = adrresponse.city;
FB.api('/me/picture', function (imgresponse) {
var picture = imgresponse.data.url;
doAjax(name, city, picture);
}
}
}
function doAjax(name, city, picture) {
//since FB API is async, the following is not correct!!!
var params = "name="+name+"&city="+city+"&picture="+picture;
//send out through AJAX.
var http = new XMLHttpRequest();
http.open("POST", url, true);
}
However, this is not ideal as you have to wait for /me/address before you can call /me/picture.
Here are some other options
you need to call /me first.
you fire off both api calls and execute code when the both complete
Ways to accomplish #2
You could then use a promise library to chain the /me/address and /me/picture/. See: https://github.com/kriskowal/q or https://api.jquery.com/category/deferred-object/ to get started
Call a callback after each that conditionally fires the ajax if both address and picture are set
I am sure there are a number of other ways:
How to chain ajax requests?
How to chain ajax calls using jquery
Update #2
This is the best way to accomplish what you are after (no additional callbacks required)
FB.api('/me', {fields: ['first_name', 'last_name', 'picture', 'address']}, function(response) {
// response will now have everything you need
console.log(response);
});
I did not give this answer originally as it was not the topic of the question which seemed to be scoping.
How would go about monkey patching the XMLHTTPRequest's onreadystatechange function. I'm trying to add a function that would be called when every ajax request made from a page come back.
I know this sounds like a terrible idea, but the use case is quite peculiar. I want to use a certain SDK with a console (jqconsole) but show status and results from ajax calls within the console without modifying the external SDK.
I've looked at this post which had great info, but nothing on monkey patching the callback which seem to exceed my JavaScript skills.
P.S Can't use jQuery since it only supports ajax calls made from jQuery not from XMLHTTPRequests directly which is the case here.
To monkey-patch XMLHttpRequests, you need to know how an AJAX request is generally constructed:
Constructor invocation
Preparation the request (setRequestHeader(), open())
Sending the request (.send).
General-purpose patch
(function(xhr) {
function banana(xhrInstance) { // Example
console.log('Monkey RS: ' + xhrInstance.readyState);
}
// Capture request before any network activity occurs:
var send = xhr.send;
xhr.send = function(data) {
var rsc = this.onreadystatechange;
if (rsc) {
// "onreadystatechange" exists. Monkey-patch it
this.onreadystatechange = function() {
banana(this);
return rsc.apply(this, arguments);
};
}
return send.apply(this, arguments);
};
})(XMLHttpRequest.prototype);
The previous assumed that onreadystatechange was assigned to the onreadystatechange handler. For simplicity, I didn't include the code for other events, such as onload. Also, I did not account for events added using addEventListener.
The previous patch runs for all requests. But what if you want to limit the patch to a specific request only? A request with a certain URL or async flag and a specific request body?
Conditional monkey-patch
Example: Intercepting all POST requests whose request body contains "TEST"
(function(xhr) {
function banana(xhrInstance) { // Example
console.log('Monkey RS: ' + xhrInstance.readyState);
}
//
var open = xhr.open;
xhr.open = function(method, url, async) {
// Test if method is POST
if (/^POST$/i.test(method)) {
var send = this.send;
this.send = function(data) {
// Test if request body contains "TEST"
if (typeof data === 'string' && data.indexOf('TEST') >= 0) {
var rsc = this.onreadystatechange;
if (rsc) {
// Apply monkey-patch
this.onreadystatechange = function() {
banana(this);
return rsc.apply(this, arguments);
};
}
}
return send.apply(this, arguments);
};
}
return open.apply(this, arguments);
};
})(XMLHttpRequest.prototype);
The main techniques used is the transparent rewrite using...
var original = xhr.method;
xhr.method = function(){
/*...*/;
return original.apply(this, arguments);
};
My examples are very basic, and can be extended to meet your exact wishes. That's up to you, however.
Assuming you can ignore IE...
//Totally untested code, typed at the SO <textarea>... but the concept *should* work, let me know if it doesn't.
var OldXMLRequest = XMLHttpRequest;
// Create a new instance
function XMLHttpRequest() {
var ajax = new OldXMLRequest();
// save old function
var f = ajax.onreadystatechange;
ajax.onreadystatechange = function() {
console.log("Whatever!");
f(); // Call the old function
}
return ajax;
}
you can learn from Ajax-hook written by chinese!
it is a advanced js to enable Monkey patch XMLHTTPRequest