Undefined jscript in javascript - javascript

I have created an ASP.Net application. I am using a javascript which is written in a separate file. I am using Var myvariableName ={} in javascript file.
I have included this file in MasterPage and accessing myvariableName in my aspx page.
This is working fine in Google Chrome, however, in IE 8 an unhandled exception is thrown as
myvariableName is undefined.
the error shows as;
0x800a1391 - Microsoft JScript runtime error: 'Common' is undefined
where Common is my javascript variable.
Please assist me in resolving this issue.

You're probably accessing the variable before your external script is executed.
Be sure to access your variable as soon as the document is fully loaded (i.e. $(document).ready(function(){...}); if you use jQuery) or try to find out the real execution order with some alert (that shouldn't be browser-depentent, by the way!).

If your code is already in a document.load or $(document).ready(function) you can always
handle the variable before acessing it via
if (typeof myvariableName !== "undefined") {
// do stuff
}
Some times in IE shit happens and window.load gets screwed specially when async calls are in place.

You are probably getting this error due to a missing semicolon. Change the code to this:
var myvariableName = {};

In your asp page, where you access your custom variable, wrap your code with:
var myvariableName = {};
window.onload = function(){
// your code here where you're accessing the variable
};

Related

Casper JS: TypeError: 'null' is not an object

I am trying to grab the "David Welsh" text on this page: http://foster.uw.edu/faculty-research/directory/david-welsh/
When I do document.getElementById('Boundless').children[0].children[2].children[0].children[1].children[0].innerHTML in the browser console, I successfully select the text I want, but when I run my js file in Terminal, I get the error:
TypeError: 'null' is not an object (evaluating 'document.getElementById('Boundless').children')
Why is this working in my browser but not in my local js file?
casper.then(function(){
this.each(links,function(self,link){
self.thenOpen(link,function(a){
this.echo(this.getCurrentUrl());
var name = document.getElementById('Boundless').children[0].children[2].children[0].children[1].children[0].innerHTML;
casper.echo(name);
}
});
});
});
CasperJS is built on top of PhantomJS which has two contexts. The page context (casper.evaluate()) is sandboxed. It is the only way to access the DOM, you need to use it.
var name = casper.evaluate(function(){
return document.getElementById('Boundless').children[0].children[2].children[0].children[1].children[0].innerHTML;
});
casper.echo(name);
Everything that you want to use inside of it, you have to explicitly pass in. It has no access to variables defined outside.
The PhantomJS documentation also has something important to say:
Note: The arguments and the return value to the evaluate function must be a simple primitive object. The rule of thumb: if it can be serialized via JSON, then it is fine.
Closures, functions, DOM nodes, etc. will not work!

Javascript: 'window' is not defined

I'm trying to learn JavaScript, but the following code has been giving me a lot of trouble:
window.onload = function () {
for ( var i = 0; i < seats.length; i++) {
for ( var j = 0; j < seats.length; j++) {
document.getElementById(getSeatId(i, j)).onclick = function(evt) {
getSeatStatus(getSeatId(i, j));
};
}
}
document.getElementById("search").onclick = findSeat;
document.getElementById("male_search").onclick = findMaleSeats;
initSeats();
};
It is from an external JS file and it is the only file linked to the page. findSeat, findMaleSeats, getSeatId, and initSeats are all defined a little bit later in the file. When I double click this file, I get the following error:
Windows Script Host
Error: 'window' is not defined
Code: 800A1391
I already tried moving the code to other places in the file, assigning a different function (even an empty function) to window.onload and many other things. It just seems that my computer doesn't know what window is. And if I try to open the HTML in a browser the nothing loads (as one would expect).
Does someone know what is wrong with this?
The window object represents an open window in a browser. Since you are not running your code within a browser, but via Windows Script Host, the interpreter won't be able to find the window object, since it does not exist, since you're not within a web browser.
It is from an external js file and it is the only file linked to the page.
OK.
When I double click this file I get the following error
Sounds like you're double-clicking/running a .js file, which will attempt to run the script outside the browser, like a command line script. And that would explain this error:
Windows Script Host Error: 'window' is not defined Code: 800A1391
... not an error you'll see in a browser. And of course, the browser is what supplies the window object.
ADDENDUM: As a course of action, I'd suggest opening the relevant HTML file and taking a peek at the console. If you don't see anything there, it's likely your window.onload definition is simply being hit after the browser fires the window.onload event.
Trying to access an undefined variable will throw you a ReferenceError.
A solution to this is to use typeof:
if (typeof window === "undefined") {
console.log("Oops, `window` is not defined")
}
or a try catch:
try { window } catch (err) {
console.log("Oops, `window` is not defined")
}
While typeof window is probably the cleanest of the two, the try catch can still be useful in some cases.

Uncaught TypeError: Cannot read property 'value' of null, need some direction

I have been trying to figure out this particular problem in my developer tools, but I've had no luck thus far. I have an error on one of my js files that says
Uncaught TypeError: Cannot read property 'value' of null
The following error refers to the 1st variable of dt_version below. The particular thing is if I comment out the first line of code. I get the same error on the following variables of offload1 and offload2. The variable is a number that I am trying to get passed over. I run this function on my body when the page loads...onload=updatetotal();
function updatetotal() {
var dt_version = document.getElementById("dt_version").value-0;
var offload1 = document.getElementById("capacity_offload1").value-0;
var offload2 = document.getElementById("capacity_offload2").value-0;
var offload3 = document.getElementById("capacity_offload3").value-0;
}
If a run an if statement looking for document.getElementByID("dt_version");...it defaults to false..so its not being carried over though on the previous page, I can see its input fine with the value in it. What am I missing here guys?
This error means that the id dt_version does not exist. Check your html to make sure it is there:
var dt = document.getElementById("dt_version");
if (dt){
// do your stuff
}else {
console.log("dt does not exist")
}
Another cause for this error may be- as you are calling the javascript function on page load there is a possible chance that your control is not yet completely rendered to the page. A simple solution is just move that control to the beginning of the page. If it doesn't work then an reliable solution is, call the function inside jquery $(document).ready().

Safari generates "Can't find variable" error although it is already defined in another Javascript page

The JavaScript script works with Chrome and Firefox but not in Safari. The code is:
$(document).ready(function(){
$(window).load(function() {
myVariable.start();
});
This generates:
ReferenceError: can't find variable: myVariable
The variable is defined in another JavaScript page that is included in this page, but for some reason Safari doesn't see the definition in the other page. Is Safari executing this script without loading the page that the variable is defined in?
How can I fix this?
Thanks for any help
Try to avoid setting global variables.
Maybe try assigning your variable to the window object, on top of the page:
window.myVariable = { start: function() {} };
Then when you need it:
$(window).load(function() {
window.myVariable.start();
});

variable assignments using jQuery failing in Safari?

I'm using jQuery 1.3.2 and it's breaking under Safari 4 for mysterious reasons.
All of my javascript references are made right before the tag, yet with the following code:
var status = $('#status');
status.change( function(){ /* ... */ } );
The following error is displayed in the Web Inspector:
TypeError: Result of expression 'status.change' [undefined] is not a function.
However the error is not encountered if I eliminate the variable assignment attach the change method directly like so:
$('#status').change( function(){ /* ... */ } );
Why? I need to use variables for this and several other findById references because they're used many times in the script and crawling the DOM for each element every time is regarded as bad practice. It shouldn't be failing to find the element, as the javascript is loaded after everything except and .
Try changing the variable to something other than "status."
It's confusing your variable with window.status (the status bar text). When I typed var status = $('#status') into the debugging console, the statusbar changed to [Object object]. Must be a bug in Safari.
If you put the code inside a function, so that status becomes a function-local variable, it should work.
It's standard practice in jQuery to wrap things in a
$.onready(function() {
});
This makes sure the DOM is loaded before you try to manipulate it.

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