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Best way to call function inside of another function JavaScript/JQuery?

I have built function that checks if record exist in local storage, if not trigger ajax call to get the data. Once data is returned I set the data in local storage. After this function completes I have to pass the data to another function that will feed the data in the form. I'm wondering what is the best practice now days to achieve this? I see more object oriented JavaScript now days and I'm wondering if any of OOP methods can be applied in this case. Here is example of my fucntion:
function getData(fnName,storageID,recID){
var inStorage = localStorage.hasOwnProperty(storageID) ? true : false,
frmData;
if(inStorage) {
frmData = JSON.parse(localStorage.getItem(storageID));
}else{
$.ajax({
type: 'POST',
url: 'AjaxFunctions.cfc?method='+fnName,
data: {'recID':recID},
dataType: 'json',
async: false
}).done(function(obj){
if(obj.STATUS == "200"){
var storageData = $.isEmptyObject(obj.DATA) ? null : JSON.stringify(obj.DATA);
localStorage.setItem(storageID,storageData);
frmData = storageData;
}else{
$('#error').html(obj.MESSAGE);
}
}).fail(function(jqXHR, textStatus, errorThrown){
alert("Error: "+errorThrown);
});
}
//frmFeed(frmData);
return frmData;
}
Function above once completed should pass the data in another function that will populate the form:
function frmFeed(frmData){
//Loop over frmData and populate the fields
}
I know the one way to accomplish this is to simply call frmFeed inside getData function that I showed above (commented code). is there any other way to call frmFeed and pass the data? If anyone can provide some example please let me know. Thank you!

There are several ways:
Callbacks
Promises
Not recommended would be to use synchronous ajax requests because it will block the UI.
Here's an implementation using promises:
function getData(fnName,storageID,recID){
return new Promise(function(resolve, reject) {
var inStorage = localStorage.hasOwnProperty(storageID) ? true : false;
if (inStorage) {
resolve(JSON.parse(localStorage.getItem(storageID)));
} else {
$.ajax({
type: 'POST',
url: 'AjaxFunctions.cfc?method='+fnName,
data: { 'recID': recID },
dataType: 'json'
// removed sync
}).done(function(obj){
if(obj.STATUS == "200"){
var storageData = $.isEmptyObject(obj.DATA) ? null : JSON.stringify(obj.DATA);
localStorage.setItem(storageID,storageData);
resolve(storageData);
}else{
$('#error').html(obj.MESSAGE);
// or reject here
reject(obj);
}
}).fail(function(jqXHR, textStatus, errorThrown){
alert("Error: "+errorThrown);
// or reject may be better here
reject({ 'jqXHR': jqXHR, 'textStatus': textSTatus, 'errorThrown': errorThrown });
});
}
});
}
getData('blah', 'storageId', 'recId')
.then(function(frmData) {
frmFeed(frmData);
});

CefSharp - Get result of AJAX request

I am really new to CefSharps Chromium browser and have difficulty figuring out how to get the result of a jquery ajax request.
My first attempt was to pass my AJAX requesto to EvaluateScriptAsync. In fact the script works. It does exactly what I want, but I do not get any results/status codes, because my Cef-Task does not wait until AJAX has completed its work.
Here an example (just a sample code):
var tasks = pdBrowser.EvaluateScriptAsync(#"
(function(){
$.ajax({
type: ""POST"",
dataType: ""json"",
cache: false,
url: ""_resources/php/ajaxRequests.php"",
async: false,
data: {
action: ""insertCrossPlatform"",
type: """",
values: JSON.stringify(""foo bar"")
},
success: function(response) {
if (typeof response === 'string' && response.substring(0, 5) == ""ERROR"")
{
return response;
}
else
{
//pageReload();
return ""OK"";
}
},
error: function(xhr, textStatus, errorThrown) {
return errorThrown + ""\n"" + xhr.responseText;
},
complete: function() {
return ""COMPLETE"";
}
});
})();", null);
tasks.ContinueWith(t =>
{
if (!t.IsFaulted)
{
var response = t.Result;
if (response.Success)
{
if (response.Result != null)
{
MessageBox.Show(response.Result.ToString());
}
}
else
{
MessageBox.Show(response.Message, "Ein Fehler ist aufgetreten", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
}
}, TaskScheduler.Default);
Afterwards I have read that there is a SchemeHandler, but I do not properly understand how to implement it. Can anyone help me out?
Thanks in advance.

Firstly SchemeHandler is unlikely to be suitable in this scenario, you would typically implement a SchemeHandler when your providing the response.
Most people choose to bind an object, and call a method on their bound object when they wish to communicate with the parent application. See the FAQ for an example. https://github.com/cefsharp/CefSharp/wiki/Frequently-asked-questions#3-how-do-you-expose-a-net-class-to-javascript
With 49.0.0 you can implement ResponseFilter to gain access to the underlying response buffer, it's complex and not well documented, so if your not comfortable digging through reference C++ code then this option isn't for you. Here's a reference https://github.com/cefsharp/CefSharp/blob/cefsharp/49/CefSharp.Example/Filters/PassThruResponseFilter.cs#L17

Something that I did was create an element on the page through javascript with an ID that is the response of the ajax call. So for example, when you make an ajax call assign an ID to the ajax call.
When the ajax call returns, write an element on the page with the pre-assigned id and callback information. Then you can just use cefsharp to read the element content from the page and this will be your callback information.
var myDivElement =document.getElementById('textareaInfo');
if( myDivElement === null)
{
var input = document.createElement('textarea');
input.id = "textareaInfo";
input.value = "Test"
input.rows="4";
input.cols="50";
input.style="height:100%;width:900px;"
var dom = document.getElementsByClassName("page-body")[0];
dom.insertAdjacentElement('afterbegin', input)
}
Then later with ajax
var root = 'https://jsonplaceholder.typicode.com';
var _holder = callbackObj;
callbackObj.showMessage(""ajax"");
$.ajax({
url: root + '/posts/1',
contentType: 'application/json; charset=utf-8',
method: 'GET',
complete: function(data){
},
success: function(response) {
$(#'textareaInfo').value(response);
}
}).then(function(data) {
callbackObj.showMessage(data);
});
Then read the texarea from cefsharp in c#
chromeBrowser.GetMainFrame().EvaluateScriptAsync(function()...$(textareaInfo).value).Result

You can use PostMessage javascript method to notify .NET application:
CefSharp.PostMessage('Your data Here');
Here is .NET code example for headless browser:
var browser = new ChromiumWebBrowser("", null, RequestContext);
browser.JavascriptMessageReceived += (sender, e) =>
{
if ((string)e.Message.notificationid == "notification1")
{
// Your processing code goes here
}
};
browser.Load(destinationUrl);
browser.ExecuteScriptAsync("(function() { ... ; CefSharp.PostMessage({data: data, notificationid: 'notification1'});})()");

how to find which method is causing the error during parallel ajax call

I am using $.when to make parallel ajax call to webapi controller and it works perfectly fine. The structure is given below,
$.when(GetDataFromMethodA(),GetDataFromMethodB(),GetDataFromMethodC())
.done(function (responseFromMethodA,responseFromMethodB, responseFromMethodC) {
if (responseFromMethodA != null) {
//do some action
}
if (responseFromMethodB != null) {
//do some action
}
if (responseFromMethodC != null) {
//do some action
}
}).fail(function (xhr, textStatus, errorThrown) {
//which method raised the exception?
});
Methods:
function GetDataFromMethodA() {
var Request = {};
Request.Code = name.find(':selected').val();
return $.ajax({
url: 'api/Data/GetCurrentView',
type: 'POST',
dataType: 'json',
data: Request
});
}
similarly, I have method B and C.
QUESTION:
There are situations where any one of the method fails and based on the failing method, I need to display appropriate message to the user. When anyone of the method fails, the exception is caught in the 'fail' section. But, how to find which method raised the exception?

If you use always instead of done, you can inspect whether the request succeeded with isResolved() or isRejected(), for instance:
$.when(GetDataFromMethodA(),GetDataFromMethodB(),GetDataFromMethodC())
.always(function (responseFromMethodA,responseFromMethodB, responseFromMethodC) {
if(responseFromMethodA.isRejected()) {
console.log('A did not work!');
}
if(responseFromMethodB.isRejected()) {
console.log('B did not work!');
}
// ...etc.
});

Parse XML catch block not catching exception in JS

I have a function that takes an XML file (obtained via AJAX) as input, parses it as XML and then execute some functions on it. A stripped down version can be found below.
AJAX
$.ajax({
type: "GET",
url: "./default.xml",
dataType: "xml",
success: function(data) {
parseMech(data);
}
});
parseMech function
function parseMech(xml) {
try {
var xmlObject = $(xml);
// See the output function below
$(".tree.base").html(treeBuilder(xmlObject.find("node").first()));
console.log("succes?");
} catch(e) {
$("#error-msg > .the-msg").text(" Invalid XML structure").parent().fadeIn(250);
console.log("Failed");
}
}
treeBuilder function
function treeBuilder(nodes) {
var newList = $("<ol>");
nodes.each(function (x, e) {
var newItem = $('<li> </li>');
for (var i = 0, l = e.attributes.length, a = null; i < l; i++) {
// Don't forget to add properties as data-attributes
a = e.attributes[i];
newItem.attr("data-" + a.nodeName, a.value);
if (a.nodeName == "cat" || a.nodeName == "word") {
newItem.html('' + a.value + '');
}
}
if ($(this).children('node').length) {
newItem.append(output($(this).children('node')));
}
newList.append(newItem);
});
return newList;
}
This works as it should when default.xml is a valid xml file. However, when it's not (for instance when I leave out a closing tag) the catch blok is not executed. In other words: when executing all functions with an invalid XML as source, neither console logs are executed, even though you would expect at least one (in try or in catch) to be logged.
Am I missing something here?

You need a fail handler in your ajax call.
According to the docs, a jquery ajax call with a dataType of xml returns a xml doc, so the data stream is being parsed in the course of the ajax call.
Alter the ajax call as follows (behaviour verified):
//...
error: function() {
console.log("ajax failed!");
},
//...
Note
Consider to change the way you specify your handlers,as error and success attributes are deprecated:
top.$.ajax({
type: "GET",
url: url,
crossDomain: true,
dataType: "xml",
})
.fail ( function() {
console.log("ajax failed!");
})
.done ( function(data) {
console.log("ajax ok!");
parseMech(data);
});

How to get default error of ajax call

Ok, what I am trying to do is alerting ajax errors according to its error codes and I have lots of ajax calls on website so I am using global ajax error handler function.
But what I want is if some ajax call already have default errors then show there not global.
$(document).ready(function(){
$(document).ajaxError(e,xhr,opt){
if(xhr.error){
//Don't do anything
} else {
alert('You have an error');
}
}
}
First Function :
$.ajax({
type:"post",
url:"page.php",
data:"name=mohit&lastname=bumb",
error:function(){
alert('error');
}
});
Second Function :
$.ajax({
type:"post",
url:"page.php",
data:"name=mohit&lastname=bumb",
});
So in 2nd case it should show You have an error and in first case just error

Yes you can, but you have to override jQuery default $.ajax methods. Check the following code that I used in one of my projects. Make sure you load the script just after jQuery.
My scenario was -
The web site had a lot of ajax partial views which had to check whether user is logged in or not. So I had to override jquery calls to check for it.
I also had to show a loader when any ajax call was made.
One more thing, some js are loaded by ajax, so I added a check whether the url is a .js file or normal url.
I have taken out the sensitive codes that were confidential for my project. The rest is here. This might help you.
$(document).ready(function () {
var oldjQuery = [];
oldjQuery["ajax"] = $.ajax;
oldjQuery["load"] = $.load;
var newOptions = [];
//override ajax
jQuery.ajax = function (options) {
newOptions["ajax"] = $.extend({}, options);
//override the success callback
newOptions["ajax"].success = function (data, textStatus, jqXhr) {
try {
if (options.url.indexOf('.js') <= -1) {
//this is a normal success call, do nothing
}
}
catch (err) {
//... my other codes, incase any error occurred
}
if (typeof options.success != 'undefined') {
//the ajax call has a success method specified, so call it
options.success(data, textStatus, jqXhr);
}
};
//override the error callback
newOptions["ajax"].error = function (jqXhr, textStatus, errorThrown) {
try {
if (options.url.indexOf('.js') <= -1) {
//this is a normal success call, do nothing
}
}catch (y) {
//... my other codes, incase any error occurred
}
//the ajax call has an error method specified, so call it
if (typeof options.error != 'undefined') {
options.error(jqXhr, textStatus, errorThrown);
}
};
return oldjQuery["ajax"](newOptions["ajax"]);
};
//override load function
jQuery.load = function (url, data, completeCallback, ignore) {
newOptions["load"].completeCallback = function (d, textStatus, jqXhr) {
try {
if (url.indexOf('.js') <= -1) {
//codes
}
} catch (err) {
try {
//codes
}catch (err2) {
}
}
if (typeof completeCallback != 'undefined') {
//call the default completed callback
completeCallback(d, textStatus, jqXhr);
}
};
return oldjQuery["load"](url, data, newOptions["load"].completeCallback);
};
});