I have a function that is parsing xml which contains javascript function calls. An example of this is:
eval(getElementText(PropValue[0]));
getElementText(PropValue[0] = top.hidePopWin()
I have followed this call up to the hidePopWin function and watched it complete from the top of the function to the bottom of the function.
Everything looks in order however I get this pesky error in Firefox: top is null
As you have probably guessed hidePopWin closes the popup window that is currently displayed.
So, hidePopWin is called and it goes through just fine (in fact the popup does in fact close), but after that is the problem. It doesn't go to the next step. I get the top is null message in Firefox (firebug) and it just stops.
The only other thing I need to mention is that this whole process starts on a double click event (legacy code). There is also a single click event that fires as well. At first I thought maybe that was the issue, however, I took out the reference to the onclick event and I still get the same message.
So I'm thinking that it has something to do with the eval statement. Just for more information I am placing a console.log("1") above the eval statement and a console.log("2") below the eval. The "1" prints, the "2" does not.
Does anyone have any ideas as to what might be the issue?
Update:
if(getElementText(PropValue[0]) == "top.hidePopWin();"){
console.log('here');
top.hidePopWin();
console.log('end');
}else{
console.log(getElementText(PropValue[0]));
eval(getElementText(PropValue[0]));
}
OK I tried the above... I see the "here" statement, but it still says top is null. The "end" statement never prints. When I click on the top is null in FF it highlights the eval statement??? So I don't know what the heck is going on.
no, but could you change the code to directly execute the code outside eval and test?
So, change, eval(getElementText(PropValue[0]));
to
top.hidePopWin();
see if you get the same error.
is 'top' visible in that scope if you breakpoint in FF (on the console.log('here') line? It's sounding like there is no such variable (I don't know why the popup closes though).
OK... This may not be the best way to go, but I did finally get it to work. Per the suggestion to change the code to run top.hidePopWin(). I tried those suggestions however I was still getting the top is null issue.
In desperation I took out the "top." and now it works. So I'm guessing there was not a "top" variable (wierd notation in my opinion).
So now I'm capturing if the string is equaling "top.hidePopWin()" and then instead of calling the eval I'm just calling the function hidePopWin();
Seems to work. Let me know if there is another way of going about this.
Related
I am still new a Javascript tried earching and tried the development tool in Chrome, too see if I could find the problem.
Working in Intellij IDEA 13, Java, javascript and xhtml.
My problem is that I have a piece of javascript, then in IDEA when moused over, says that
Expression Expected
the javascript code looks the following
<script type="text/javascript>
function nameOfFunction(){
if(#{trendAnalysisLocationReportController.model.showTargetLine}){
this.cfg.series[this.cfg.data.length-1].pointLabels = {
show: false
};
}
}
<\script>
the method in the if sentence is a java method with a boolean return value.
the error is shown when hovering
'#{'
if Had a look at the following questions, before :
Expected Expression
boolean in an if statement
But didnt get me a solution.
what Iam I doing wrong ?
It looks as though the problem is the part that you've got within the #{...} block. Without knowing the context, it's hard to be sure, but is this something in a view/JSP page that's supposed to be replaced with a property at runtime? The if block will expect the part inside the brackets to be a boolean value, so if that's rendered to either 'true' or 'false' it would execute at runtime but would likely show the error you're seeing in your IDE as it's not actually a valid piece of JavaScript. If, on the other hand, you're expecting to be able to call your Java method/property from your JavaScript code, you're going to need to do something that requests that value from the server-side code - AJAX or similar.
Also worth noting that we can't see what this.cfg is supposed to represent. If that's your entire script block, then there's nothing that defines the cfg object within the current scope.
One last thing, you should change the <\script> end element to as it won't be understood properly by some browsers.
I have a breakpoint on this piece of code (using Firebug):
if (validator.formValidate([dom.forumid]))
How can I skip this validation part and get into the if clause even if my dom.forumid is not valid, i.e. the call to formValidate() returns false? So how can I make it return true?
I was thinking about modifying the JavaScript, but I don't know how that's done.
As of today (Chrome 67) you can just double-click any variable on the right hand side under the "Scope" section and edit it in real-time.
In Firebug I do this by entering an assignment into the watch input field
to assign a new value
to assign a new function that returns the value I expect
This also works in Chrome ~33 (just tested) execpt: one has to enter the assignment into the console (which actually works in Firefox too, but using the watch panel is faster :).
In Firebug, you have to edit and re-save the assignment typed into the input on each break.
Of course, replacing the function will prevent the code from functioning normally on further runs. To avoid this one might save the original value to window._savedFnX or so and then do the assingment again assigning the saved function/value. But I think this is a workaround from saving one stepping through the code again and again to reach the point of interest. I often realize that there's a bad condition and then I want to continue (while the code would not) to test the rest of the code.
Take a look at these screenshots:
Code background
In the screenshot photo is an instance with this code:
{
...
_loaded: false, // set to true on some condition
...
isLoaded: function(){
return this._loaded;
},
...
}
The method isLoaded() will be replaced in the example to always return true. :)
Firebug
(Applies to Firebug ~1.12)
Stop at breakpoint
Go to the console
Assign function that returns the value you want to the variable in scope (or being reachable) [ORANGE]
The [BLUE] box highlights the the value that would be returned by isLoaded() and the value that is being returned by the replaced function.
Chrome
(Applies to Chrome ~34.0)
Note: in Chrome you can also edit the source code and re-run the modified version.
Stop at breakpoint
Go to the console
Assign function that returns the value you want to the variable in scope (or being reachable) [ORANGE]
(Refresh to see the result) [GREEN]
The [BLUE] box highlights the the value that would be returned by isLoaded() and the value that is being returned by the replaced function.
This is my first question on stackoverflow so hopefully I'm doing it right.
I ran into an issue where a variable was passing a seemingly strange value through a click event. I figured out a different way to do it, but I'm curious as to why my original method wasn't working. I have a feeling it is a weird scoping rule of JS, so if someone could clarify, that would be great. The code was supposed to switch back and forth between two tabs on a click event. I'm sorry if this has already been answered, but in looking at others' questions I couldn't really tell if it was the same issue that I was having.
This was my original code, where at program start tab1 had the class active-tab:
$("#tab1").on('click', {activeTab: $("#tab1").hasClass("active-tab"),
tab1Clicked: true}, changeTab);
$("#tab2").on('click', {activeTab: $("#tab1").hasClass("active-tab"),
tab1Clicked: false}, changeTab);
and elsewhere
function changeTab(event) {
var tab1Active = event.data.activeTab;
var tab1WasClicked = event.data.tab1Clicked;
if(tab1Active) {
if(tab1WasClicked)
alert("tab1 active & clicked, no change");
else {
alert("tab1 active, tab2 clicked, change");
$("#tab1").removeClass("active-tab");
$("#tab2").addClass("active-tab");
}
}
else {//tab2 is active
if(tab1WasClicked) {
alert("tab2 active, tab1 clicked, change");
$("#tab2").removeClass("active-tab");
$("#tab1").addClass("active-tab");
}
else
alert("tab2 active & clicked, no change");
}
}
The problem was that, although the .hasClass calls returned the correct result, the value of event.data.activeTab always turned out to be true, so once tab2 got clicked it never made tab1 active again because it always thought it already was, even though the class did in fact get removed. I solved this by passing only tab1Clicked through event.data and just checking $("#tab1").hasClass("active-tab") directly in the function changeTab, which is probably what I should have been doing from the beginning, but still, can someone explain to me why this other method didn't work equally well?
The "data" expressions are evaluated once, at the point where the event handler is set up. They aren't (and can't be) re-evaluated for each actual event. This code:
$("#tab1").on('click', {activeTab: $("#tab1").hasClass("active-tab"),
tab1Clicked: true}, changeTab);
is evaluated by computing the value expressions for that data object. What's passed to the jQuery .on() function therefore is an object with two properties, each with a fixed value (booleans, in this case). They'll never change after that, because there's no trace of the expressions that initialized the property values.
In this case, the simplest solution is to simply move the tests into the function, as you say.
I'm having one little iritating problem. I have simple if condition in javascript code.
It goes something like this:
if (istinito)
{
alert ('123');
document.getElementById('obavestavanje').value="Pobedi "+ime_igraca+"!!!";
kraj=true;
}
Alert apears when istinito=true, but element with id="obavestenje" never get its value, and variable kraj never is set to true. Variable kraj is global variable, and there are no conflicts with other parts of the JS code.
Any ideas why code stops after alert?
Looks like document.getElementById('obavestavanje') is returning null. You are trying to de-reference the null reference by using document.getElementById('obavestavanje').value which results in null pointer exception. If you look into the console, you should see some exception being raised. It is always a good idea to check if the document.getElementById() is returning a valid object before trying to dereference it.
e.g.
if (istinito)
{
alert ('123');
element = document.getElementById('obavestavanje')
if(element){
element.value="Pobedi "+ime_igraca+"!!!";
}
kraj=true;
}
First advice i could give you:
Use more console logging for debugging. Almost any modern browser got a console to debug and other things.
if (istinito) {
console.log("i am here");
}
from that same console you can also execute commands. Those dom manipulations are easily done from the console. just run them and see if it works.
the code:
document.getElementById('obavestavanje').value = "some value"
looks ok. nothing wrong with it. i guess you don't have an element with id "obavestavanje" ?
Looks like your code is okay. And you are sure you have an element by id 'obavestavanje'. Could you please tell what element is it? Is it a button, textbox or someting like that?
Also the String in the "Pobedi "+ime_igraca+"!!!" , what is 'ime_igraca'? Is it a variable and if it is have you defined this variable somewhere?
Or did you mean to give the value "Pobedi ime_igraca !!!" ??
Thanks
Ranis MK
if (1) {
google_conversion_value = 1;
}
What is the meaning of the above statement? I mean, this looks like it will always execute so why bother with the if statement?
updated: one reason might be remnants of scripting on the server side. Any other ideas?
updated2: could as easily change the value of the assignment without bothering with the if statement, no?
There are two likely explanations:
It's a leftover from debugging.
The file containing this code is generated dynamically and the original sourcecode contains something like if(<?php echo $some_stuff_enabled; ?>)
However, in the latter case it would have been cleaner to output that code block only if the condition is met - but maybe it's used in some crappy template engine that just allows replacements but no conditionals...
I've seen this before, and I've always assumed it was a remnant of some old condition that was no longer needed, but never removed. I can't see any actual reason to do something like that otherwise.
Potentially because the person writing the code wanted an easy way to turn it off and on again, this is especially useful if there is a lot of code inside the block (not the case here).
Another possibility is that the original programmer couldn't be bothered writing the logic or, more likely, it hadn't been specified so the "if" was left as a placeholder.
More than likely left in from a debug release or something similar. You're right, it will always execute. It could also have been done like this so that it can be easily enabled / disabled by setting the if to 0. Perhaps the developer intended to use it as a flag somewhere else in the code?
actually, this happens when the "if" condition is driven from server, so instead of doing the right thing and not produce the script when the condition is false, they do something like this:
if (<% if (my_server_condition) then Response.Write("1") else Response.Write("0") %>){
// code goes here
}
Perhaps the if statement used to check for a legitimate conditional, and then someone replaced it with a truthy value for testing/debugging/etc.
You're right, it will always execute because 1 is truthy. I would go through your source control history and investigate that line to see if it used to contain a real conditional. If the conditional was always 1, then it's likely a debugging statement. Otherwise someone might have meant for it to be a temporary change, and may not have meant to check that in (which could be bad).
I'm not sure where this code is from, but as you indicated it will always execute. As for why you'd do this, there are times where you want to see what the result of branch code would be, without having to setup an environment. In this case you can comment out the actual value and replace it with if(1) instead for testing:
// if( ... some hard to achieve condition )
if (1) {
// Now you can see what happens if this value is set quickly
google_conversion_value = 1;
}
Of course the problem with this is that it's sometimes easy to forget to remove the if(1) and uncomment the proper condition.
This is actually the javascript recommended by Google on http://support.google.com/adwords/bin/answer.py?hl=en&answer=1722054#nocomments (click on Step 2 for the sample HTML)