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SyntaxError: expected expression, got ')'

I've been stuck at this error for a few days and still couldn't figure out what is wrong. Would be great if someone could just point me to the right direction of solving this issue.
Update:
I realise that error is gone when I commented "addMessages(xml)" in the updateMsg() function. How do I make it work then?
Error:
http://i.imgur.com/91HGTpl.png
Code:
$(document).ready(function () {
var msg = $("#msg");
var log = $("#log");
var timestamp = 0;
$("#name").focus();
$("#login").click(function() {
var name = $("#name").val();
if (!name) {
alert("Please enter a name!");
return false;
}
var username = new RegExp('^[0-9a-zA-Z]+$');
if (!username.test(name)){
alert("Invalid user name! \n Please do not use the following characters \n `~!##$^&*()=|{}':;',\\[\\].<>/?~##");
return false;
}
$.ajax({
url: 'login.php',
type: 'POST',
dataType: 'json',
data: {name: name},
success: function() {
$(".login").hide();
}
})
return false;
});
$("#form").submit(function() {
if (!msg.val()) {
return false;
}
$.ajax({
url: 'add_message.php',
type: 'POST',
dataType: 'json',
data: {message: msg.val()},
})
msg.val("");
return false
});
window.setInterval(function () {
updateMsg();
}, 300);
function updateMsg() {
$.post('server.php', {datasize: '1024'}, function(xml) {
addMessages(xml);
});
}
function addMessages(xml) {
var json = eval('('+xml+')');
$.each(json, function(i, v) {
tt = parseInt(v.time);
if (tt > timestamp) {
console.log(v.message);
appendLog($("<div/>").text('[' + v.username + ']' + v.message));
timestamp = tt
}
});
}
function appendLog(msg) {
var d = log[0]
var doScroll = d.scrollTop == d.scrollHeight - d.clientHeight;
msg.appendTo(log)
if (doScroll) {
d.scrollTop = d.scrollHeight - d.clientHeight;
}
}
});

It might help to read up on eval a bit. It looks like it doesn't do what you think it does.
eval() is a dangerous function, which executes the code it's passed with the privileges of the caller.
Also
There are safer (and faster!) alternatives to eval() for common use-cases.
It looks like what you're trying to do is get data from the server in the form of JSON. You'll need to make sure that your server returns something that is valid JSON, which you can verify here. Most server-side programming languages have a library that will turn an object into JSON to make that a piece of cake. Here's an example for php.
On the client-side, you'll need to change var json = eval('(' + xml + ')'); to var json = JSON.parse(xml); This will give you the javascript version of your php/perl/python/etc object. If it's an array, you can then iterate through it with a for loop, Array.prototype.forEach, or a variety of functions from different libraries, such as $.each or _.each.

SyntaxError: expected expression, got ')' usually cause by something like
exeFunction(a,b,)
See if your form submit function ajax causing such error
$("#form").submit(function() {
if (!msg.val()) {
return false;
}
$.ajax({
url: 'add_message.php',
type: 'POST',
dataType: 'json',
data: {message: msg.val()}, <-------
})
msg.val("");
return false
});

If you are triggering the java script on click or trigger any click. sometimes missing of 0 gives the above error.
delete

would JSON.stringify({datasize: '1024'}) do the trick? just a guess

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 do i wait for multiple ajax calls to complete from a .each loop

I am running a loop that updates records on a table but i need to wait for all of the records to update before i continue on.
How can I have jquery wait until all of the calls in the loopselectedrows function completes? I have read about .deferred and .when but i am not sure how to implement
either. they both do not seem to able to handle an array of calls if i where to change over to using an array for the ajax posts. Any help would be greatly appreciated.
this is the button that starts it all :
click: function () {
// validate all rows
var $selectedRows = $('#Table1').jtable('selectedRows');
LoopSelectedRows($selectedRows, 'Validate');
/// wait here until all ajax calls have completed
// then continue with checking
// check for any row with an error
var $ValidatedRows = $('#Table1').jtable('selectedRows');
var boolCheck = checkValidatedRows($ValidatedRows);
// if all records are succesfull then add them
// else alert user
if (boolCheck == true) {
LoopSelectedRows($selectedRows, 'Add');
}
else {
alert("Please correct invalid records and try again");
}
}
the first thing this does is take all of the records from the table and passes them to a looping function.
this is the looping function -
function LoopSelectedRows(SelectedRecords, actionType) {
if (SelectedRecords.length > 0) {
//Show selected rows
SelectedRecords.each(function () {
var record = $(this).data('record');
record.PERSON_NAME = record.PERSON_ID;
// Actions for loop
// Validation Action
if (actionType == 'Validate') {
check = validateRecord(record);
}
// call add function
if (actionType == 'Add') {
AddRecordToTable(record);
}
})
};
}
this loop can either validate or add records for now i am only worried about the validation function
this is the validation function:
function validateRecord(dataRecord) {
$.ajax({
url: "./ValidateAddRecord",
type: 'POST',
contentType: 'application/json',
dataType: 'json',
data: JSON.stringify(dataRecord),
success: function (data) {
if (data.Result == "OK") {
// update record with message
$('#table1').jtable('updateRecord', { record: data.Record });
}
else {
// display error
alert(data.Message);
}
}
});
}

One fairly clean way to know when multiple ajax calls are done is to use promises and jQuery's $.when(). That will give you a callback when all the ajax calls are done. It will take a little bit of reorganization of your code to use that.
First, you return the $.ajax() promise from validateRecord():
function validateRecord(dataRecord) {
return $.ajax({
url: "./ValidateAddRecord",
type: 'POST',
contentType: 'application/json',
dataType: 'json',
data: JSON.stringify(dataRecord),
success: function (data) {
if (data.Result == "OK") {
// update record with message
$('#table1').jtable('updateRecord', { record: data.Record });
}
else {
// display error
alert(data.Message);
}
}
});
}
Then, you collect all the promises in LoopSelectedRows() and return a master promise using `$.when():
function LoopSelectedRows(SelectedRecords, actionType) {
var promises = [];
if (SelectedRecords.length > 0) {
//Show selected rows
SelectedRecords.each(function () {
var record = $(this).data('record');
record.PERSON_NAME = record.PERSON_ID;
// Actions for loop
// Validation Action
if (actionType == 'Validate') {
promises.push(validateRecord(record));
}
// call add function
if (actionType == 'Add') {
promises.push(AddRecordToTable(record));
}
})
};
// return master promise
return $.when.apply($, promises);
}
Then, you can use that final promise to know when everything is done.
click: function () {
// validate all rows
var $selectedRows = $('#Table1').jtable('selectedRows');
LoopSelectedRows($selectedRows, 'Validate').then(function() {
// all the ajax calls in LoopSelectRows are done now
// check for any row with an error
var $ValidatedRows = $('#Table1').jtable('selectedRows');
var boolCheck = checkValidatedRows($ValidatedRows);
// if all records are succesfull then add them
// else alert user
if (boolCheck == true) {
LoopSelectedRows($selectedRows, 'Add');
} else {
alert("Please correct invalid records and try again");
}
});
FYI, you probably also want to change AddRecordToTable() to return a promise so it can work the same way (though it is not required because you aren't trying to wait for that operation to be done).

$.active returns the number of active Ajax requests. Use $.active==0 means no ajax requests are active. You could also use ajaxStart and ajaxStop to keep track of when requests are active.

Thank you jfriend00, your solution seems to have solved my issues.
Below is the updated version i am now using for anyone interested :
click: function () {
// validate all rows
var $selectedRows = $('#table1).jtable('selectedRows');
LoopSelectedRows($selectedRows, 'Validate').then(function () {
// check for any row with an error
var $ValidatedRows = $('#table1).jtable('selectedRows');
var boolCheck = checkValidatedRows($ValidatedRows);
// if all records are succesfull then add them
// else alert user
if (boolCheck == true) {
LoopSelectedRows($selectedRows, 'Add');
}
else {
alert("Please correct invalid records and try again");
}
});
}
// loop function
function LoopSelectedRows(SelectedRecords, actionType) {
var promises = [];
if (SelectedRecords.length > 0) {
//Show selected rows
SelectedRecords.each(function () {
var record = $(this).data('record');
// Actions for loop
// Validation Action
if (actionType == 'Validate') {
promises.push(validaterecord(record));
}
// call add function
if (actionType == 'Add') {
AddRecordToTable(record);
}
})
};
return $.when.apply($, promises);
}
// validate function
function validaterecord(dataRecord) {
var def = $.Deferred();
$.ajax({
url: "./ValidateAddRecord",
type: 'POST',
contentType: 'application/json',
dataType: 'json',
data: JSON.stringify(dataRecord),
success: function (data) {
if (data.Result == "OK") {
// update record with message
$('#table1).jtable('updateRecord', { record: data.Record });
// resolve token
def.resolve();
}
else {
// display error
alert(data.Message);
}
}
});
return def.promise();
}

AJAX "success" executing before response is returned

I'm hoping this is just a simple fix due to me being a little dumb somewhere along the line. I'm executing my ASP.NET MVC login using AJAX. There is a "success" handler which returns a "true" value to the calling function which, in turn, load the home page.
The issue is that the "success" handler is executing BEFORE any value is returned - which means that nothing happens because the value is not "SUCCESS". I can confirm this by looking at the request in Firebug, the value returned is SUCCESS but nothing happens. If I apply a breakpoint to the end of the function and then continue execution it works just fine.
I have no idea what the issue is, I'd be very grateful for help or an explanation to what I'm doing wrong.
Thanks!
My JS Function:
function LogIn(UserName, Password) {
var Cont = true;
var ErrorString = "";
if (UserName == null || UserName == "") {
Cont = false;
ErrorString += "Username is Required.";
}
if (Password == null || Password == "") {
Cont = false;
ErrorString += "Password is Required.";
}
var result = false;
if (Cont) {
var LogInUrl = "/AJAX/LogIn?UserName=" + UserName + "&Password=" + Password;
$.ajax({
url: LogInUrl,
type:"GET",
success: function( data ){
if (data == "SUCCESS") {
result = true;
}
}
})
}
return result;
}
UPDATE: The function that calls the LogIn function:
$('#FormLogin').submit(function (e) {
e.preventDefault();
var UserName = $("#TxtLoginUsername").val();
var Password = $("#TxtLoginPassword").val();
var IsLoggedIn = LogIn(UserName, Password);
if (IsLoggedIn) {
window.location.assign("/");
} else {
$('#LoginErrorContainer').show();
$('#LoginErrorContainer .error-text').html("There was a problem logging you in. Please try again.");
}
})
As I said, the function does it's job and logs me in, but the "success" handler seems to execute before the value is returned.

Change your ajax call to something like this:
$.ajax({
url: LogInUrl,
type:"GET",
success: function( data ){
if (data == "SUCCESS") {
window.location.assign("/");
} else {
$('#LoginErrorContainer').show();
$('#LoginErrorContainer .error-text').html("There was a problem logging you in. Please try again.");
}
}
});
There is no point in returning result from LogIn, it'll always be false. You need to put the code handling the returned value in the callback.
Another alternative, if you don't like the idea of your LogIn function being so closely coupled to DOM manipulation is to return the promise from your ajax call. So at the end of LogIn, you'd do something like this:
return $.ajax({
url: LogInUrl,
type:"GET"
}
});
And then when you call it, you'd do something like this:
LogIn(UserName, Password).then(function(data) {
if (data == "SUCCESS") {
window.location.assign("/");
} else {
$('#LoginErrorContainer').show();
$('#LoginErrorContainer .error-text').html("There was a problem logging you in. Please try again.");
}
});

Div content doesn't changes on first click

I have a problem with changing div's content. I make an ajax call first and receive an JSON array from server. So far, so good. Then, I want to change several div's content to what I've received from server. The problem is that content doesn't changes on the first click. Response is OK every time, I've checked with Fiddler and in my code, that I am receiving correct response. But, mystery remains why are div's on my page not changed with the first click Why I have to click twice every time? I've spend hours figuring this out, tried everything, nothing seems logical. Here's my code (project is MVC 4):
$('#btnsearch').click(function ()
{
var searchStr = $('#txtSearch').val();
var noOfPages = 1;
$.ajax({
type: "POST",
datatype: 'json',
url: $('#btnsearch').data('request-url'),/*URL from Razor's page*/
data: { pageNo: noOfPages, searchString: searchStr },/*MVC 4 call*/
success: function (jsontext)
{
$('#hiddenSearchResult').val(jsontext);
},
error: function ()
{
alert('Error when searching!');
}
});
var json = $('#hiddenSearchResult').val();
if (json.length === 0){ alert('result is empty!');
return;}/*with empty json, parsing throws error*/
json = JSON.parse(json);
if (json.Content == undefined) return;
for (var i = 0; i < json.Content.length; i++) {
switch (i) {
case 0:
$('#snippetsdivinner').html(json.Content[i].ContentString);
break;
case 1:
$('#snippetsdivinner1').html(json.Content[i].ContentString);
break;
case 2:
$('#snippetsdivinner2').html(json.Content[i].ContentString);
break;
case 3:
$('#snippetsdivinner3').html(json.Content[i].ContentString);
break;
}
}
});

The code from var json = $('#hiddenSearchResult').val() onwards is executed right after the AJAX request is started, but before it is completed, so at that time $('#hiddenSearchResult') isn't populated yet.
When you click the button for the second time, it has been populated by the completion of the AJAX request, and thus the code after your $.ajax executes as you expect.
You should move your code inside the success function to have it all executed when the AJAX request completes.

You probably need to also put all the code starting from
var json = $('#hiddenSearchResult').val();
inside the success callback of your ajax.

If you use datatype: 'json' in your ajax call, you don't have to do json = JSON.parse(json);.
And what the other answers said about putting all your code in the success callback function.

It's asynchronous, you need to wait until you have the result
$('#btnsearch').click(function ()
{
var searchStr = $('#txtSearch').val();
var noOfPages = 1;
$.ajax({
type: "POST",
datatype: 'json',
url: $('#btnsearch').data('request-url'),/*URL from Razor's page*/
data: { pageNo: noOfPages, searchString: searchStr },/*MVC 4 call*/
success: function (jsontext)
{
if (jsontext.length === 0){ alert('result is empty!');
return;
}/*with empty json, parsing throws error*/
var json = JSON.parse(jsontext);
if (json.Content == undefined) return;
for (var i = 0; i < json.Content.length; i++) {
switch (i) {
case 0:
$('#snippetsdivinner').html(json.Content[i].ContentString);
break;
case 1:
$('#snippetsdivinner1').html(json.Content[i].ContentString);
break;
case 2:
$('#snippetsdivinner2').html(json.Content[i].ContentString);
break;
case 3:
$('#snippetsdivinner3').html(json.Content[i].ContentString);
break;
}
}
},
error: function ()
{
alert('Error when searching!');
}
});
});