How can i check in JavaScript if a variable is defined in a page? Suppose I want to check if a variable named "x" is defined in a page, if I ... |
hey everybody,
i feel like im trying to do something super simple, but just being stupid about it.
all i want to do is see if a variable has been set previously, and ... |
Possible Duplicate:
Detecting an undefined object property in JavaScript
I wanted to check whether the variable is defined or not.
eg
alert( x );
Throws a not defined error
How ... |
Reading Crockfords The Elements of JavaScript Style I notice he prefers defining variables like this:
var first='foo', second='bar', third='...';
What, if any benefit does that method provide over this:
var first='foo';
var second='bar';
var ...
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If a variable could be defined in a function, even if no value is assigned, it becomes a local variable
so, is testB() better programming?
var test = 'SNAP!'
function testA(boolean) {
...
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The JavaScript script works with Chrome and Firefox but not in Safari. The code is:
$(document).ready(function(){
$(window).load(function() {
myVariable.start();
...
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I'm using the awesome JSLint tool to ensure my JavaScript is "strict".
When I use it however, I get the following errors:
'hexRed', 'hexGreen', 'hexBlue', 'color' are already defined (referring ...
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Reading documentation online, I'm getting confused how to properly define multiple JavaScript variables on a single line.
If I want to condense the following code, what's the proper JavaScript "strict" way to ... |
Saw some JS notation today that I've never seen before, bear with me if it is something common that everyone knows.
var cookiepath = cookiepath || '';
Now, is this just saying, if ... |
Wanted to get opinions from the experts, I am declaring a variable that will act as the namespace for my application javascript code, but i want to check it is not ... |
I have a form in my document (with name 'formName') and a few elements with names part text, followed by an ID, eg: an input with name 'model_'+z where z is ... |
I've been using jQuery and YUI side-by-side with no issues until recently. Occasionally, inside of a callback for, say, a YUI button, $ will be shadowed by some other function (click ... |
I have many variables in my javascript function and don't fit on one line declaration.
var query_string = $('list_form').serialize(), container = $('list_container'),position = container.cumulativeOffset(), layer = $('loaderLayer'),
...
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I've heard that it is a good technique to define your variables at the top of a function, so you don't end up with variable hoisting problems. This:
// Beginning of file
function ...
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I am writing a simple javascript function that grabs information out of three text areas. Pretty basic, but for some reason javascript is telling me that my variables are not defined ... |
I cannot understand why this code below keeps throwing a viewModel is undefined, does anyone know why?
NOTE:
I actually think this may be a problem with knockout.js, it wants the viewModel to ... |
In the following code how can I correctly insert the val testName defined in the function initialize() in the field Name in the body?
<html>
<head>
<script type="text/javascript" src="http://code.jquery.com/jquery-1.6.min.js"></script>
<script type="text/javascript">
function intialize()
{
...
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In this piece of Javascript
creds = cp[0];
data[creds.toString()] = cp[1]; // data is an object
Chrome gives me the error TypeError: Cannot call method toString of undefined on the second line. However, I've ... |
Got confused by this behaviour. I thought doing something like:
if (variable name)
{
... do this...
}
should work. However if the variable is not defined, I just get 'ReferenceError: Can't ... |
Possible Duplicate:
How can I check whether a variable is defined in JavaScript?
How should I test if a variable is defined?
if //variable is defined
...
|
A very weird problem occurred, when I was trying to enable a lib (Beard.js) to support the javascript template engine Haml.
Haml could not be loaded correctly. I tracked down the code ... |
Is it ok to define a variable like this:
var myVariableName = (var1 > 0) ? "yay" : "nay";
or is it best to wrap the varaible in the if statment:
if(var1 > 0){
...
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Possible Duplicate:
What does this construct (x = x || y) mean?
a lot of times i can see that variables set like that
var d ...
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I have a function that searches a database table via ajax.
This is the function
function find_file(query)
{
var xtoken = $("input[name='xtoken']").val();
...
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Hi, I have a programing problem that have been around for ages. I have search on google using several expressions and words and after hours of digging i'm still unable to do it. I would like to get a value from a HTML page hosted remotely with an inconstant value. Then define this value and name as a javascript variable and ... |
Defining and displayed variables with switch statement Hi, I'm trying to code a script that will display an approximate postage price based on different combinations of variables, but the numbers I defined for each case aren't reflected in the text box. I'm using a switch statement for all the different combinations of options, which the user will choose by selecting check-boxes. ... |
Hello I have a php page in which I declared a js variable... right at the top of the page... Later in the page I test this variable... But I keep getting an error variable _tester undefined Am I missing something obvious... I am new ... |
Hi all, I am relatively new to java; hence I know the basics, but have been thrown into trouble because I am currently working with a cms system that doesnt keep within the correct name conventions (pre defined). Within a form, I simply want to set a date to todays date: |