Help needed with Javascript Objects - javascript

I need some help with Javascript objects. This is what I've got:
_genre_id = {politics:'1',sport:'2',celeb:'3',gossip:'4',busi:'5'};
var genre = 'politics';
What I want to accomplish would be to simply get the value stored for politics, in this case 1 by doing something like this:
var genreID = _genre_id.genre;
But this of course doesn't work because the genre property doesn't exist. I want it to relate to _genre_id.politics.
Any ideas would be welcome.

How about _genre_id[genre]?

var _genre_id = {politics:'1',sport:'2',celeb:'3',gossip:'4',busi:'5'};
var genre = 'politics';
var genreID = _genre_id[genre];
Note that I added var before setting _genre_id, so that it gets declared in the current scope, without declaring it, you end up setting window._genre_id instead of a local variable.

Related

How to make a variable which consists of multiple 'divs'

I have a question regarding variables in Javascript.
When I assign a var to a ID I do it like this:
var x = document.getElementById("div_name");
But I would like to make a variable which consists of multiple 'divs'.
I thought this might work but I does not:
var x = document.getElementById("div_name"),document.getElementById("div_name2");
Can someone please help me find the right code syntax and explain why the syntax I tried is incorrect.
So, If you just want them as a list of div's you could do this:
var x = [document.getElementById("div_name"),document.getElementById("div_name2")];
Just wrap them up with [].
If your var should contain more than one object (div in your case), then you need to have more variable or, better, an array.
You can create yor array by using following code.
var x = [document.getElementById("div_name"), document.getElementById("div_name2")];
This is due to the fact that different DIVs in the DOM page are different objects...
There is no such variable that is defined as:
var x = somthing, somesthingElse
You need to chose a variable that can store a collection of "things". In your case the Array is an ideal choice:
var x = [document.getElementById("div_name"),document.getElementById("div_name2")];
The brackets at the beginning and end of the expression are the syntax to declare a variable.
In addition to using Array, you can also store your divs in an Object
var divs = {
div1: document.getElementById("div_name"),
div2: document.getElementById("div_name2")
};
Thus, you could give a convenient name to your divs, but still pass them around as you please:
divs.div1;
divs.div2;
Or loop through them like so:
for (div in divs) {
console.log(divs[div]);
};

Having trouble referring to object within array

I am trying to write an html page for class that uses a drop down menu to allow users to pull up a list of relevant information. Unfortunately I am having trouble figuring out how to make the script call on the information in the array. The jsfiddle has the full html section, any help would be GREATLY appreciated.
Please bear in mind that I am not very good with terminology, so be as specific as possible. Especially regarding jQuery, our teacher didn't go over it much so it's a freaking mystery to me.
Also, I do plan on adding more information to the objects in the array, but until I get it working, I don't want to waste the time on something I might need to restructure.
http://jsfiddle.net/GamerGorman20/nw8Ln6ha/11/
var favWebComics = [
Goblins = {1: "www.goblinscomic.org"},
GirlGenious = {1: "www.girlgeniousonline.com"},
GrrlPower = {1: "www.grrlpowercomic.com"}
];
var myFunction = function() {
var x = document.getElementById("mySelect").value;
document.getElementById("demo").innerHTML = "You selected: " + x;
document.getElementById("web").innerHTML = favWebComics.x;
};
Again, the JSFiddle link has the full html, there are some unused items currently, but I do plan on adding more of them soon.
My next plan is to incorporate images into the objects, so a picture loads for each selection option. How would I manage that?
[ ] is used for arrays, which are indexed with numbers. If you want named properties, you should use an object, which uses { } for its literals:
var favWebComics = {
Goblins: "www.goblinscomic.org",
GirlGenious: "www.girlgeniousonline.com",
GrrlPower: "www.grrlpowercomic.com"
};
= is for assigning to variables, not specifying property names in an object.
Then you need to understand the difference between . and [] notation for accessing objects. .x means to look for a property literally named x, [x] means to use the value of x as the property name. See Dynamically access object property using variable.
So it should be:
document.getElementById("web").innerHTML = favWebComics[x];
your array is not structured correctly and an object would be better suited:
var favWebComics = {
Goblins : "www.goblinscomic.org",
GirlGenious : "www.girlgeniousonline.com",
GrrlPower : "www.grrlpowercomic.com"
};
then you should be able to access the properties as you intend
favWebComics.Goblins
favWebComics.GirlGenious
favWebComics.GrrlPower
Technically you were treating the array like a dictionary. if you're going to do that but still wanna add more information later you'll need to use brackets {} on the code.
var favWebComics = {
Goblins: ["www.goblinscomic.org"],
GirlGenious: ["www.girlgeniousonline.com"],
GrrlPower: ["www.grrlpowercomic.com"]
};
Also for javascript, as long as your searching key value stores, use braces [] for the call. Here's the working code below.
document.getElementById("web").innerHTML = favWebComics[x];
I have your solution, that displays:
the selected choice
the url
the images
Please check the fiddle.
http://jsfiddle.net/nw8Ln6ha/13/
Your object would be:
var favWebComics = {
Goblins : {url:"www.goblinscomic.org", img:"img1"},
GirlGenious : {url:"www.girlgeniousonline.com", img:"img2"},
GrrlPower : {url:"www.grrlpowercomic.com", img:"img3"}
};
Your display code:
document.getElementById("demo").innerHTML = "You selected: "+x+" "+ eval("favWebComics[\""+x+"\"].url")+" "+ eval("favWebComics[\""+x+"\"].img");

How can I get the content of a variable that I don't know its name

Although this question is about datatables, it's not specifically about it.
I have datatables init stored in variables. The variable name varies as I have several datatables on the page. I am trying to collect the content of those variable by assembling the variable's name and I don't know how i can later use the 'string' I've assembled as a variable
For example:
var var_1_id_0 = $('.item1').datatable();
var var_1_id_1 = $('.item2').datatable();
var var_1_id_2 = $('.item3').datatable();
// later in the code.
var varname = 'var_1_id'+'_0';
// varname now holds the string 'var_1_id_0' which is the first variable.
My question is how can I use varname's string 'var_1_id_0' as the variable 'var_1_id_0'?
I hope that make sense.
Thanks
It is not possible. The closer solution is this one:
var datatable={};//A new Object.Arrays doesn't work property for this.
datatable['var_1_id_0'] = $('.item1').datatable();
datatable['var_1_id_1'] = $('.item2').datatable();
datatable['var_1_id_2'] = $('.item3').datatable();
// later in the code.
var varname = 'var_1_id'+'_0';
console.log(datatable[varname]);
Try it like this:
var varname = 'var_1_id'+'_0';
alert(window[varname]);

Javascript Computed Values With Arrays

Jquery Each Json Values Issue
This question is similar to above, but not the same before it gets marked duplicated.
After realasing how to use computed values i came across another issue.
In my javascript i have the following code:
var incidentWizard = ['page1.html','page2.html','page3.html'];
var magicWizard = ['page1.html','page2.html','page3.html'];
var loadedURL = 'page1.html';
The input to this function would be (true,'incident')
function(next,wizardname)
{
var WizSize = incidentWizard.length;
wizardName = [wizardName] + 'Wizard';
var wizardPOS = jQuery.inArray(loadedURL,incidentWizard);
And now i want to use the wizardname parameter to decide what array i am going to use...
Loader(incidentWizard[wizardPOS],true);
Ive also tried
Loader([incidentWizard][wizardPOS],true);
and
Loader([incidentWizard][wizardPOS],true);
Also the loader function just required the string value in the array at wizardPOS sorry for confusion
But when trying this i always end up with the outcome...
/incidentWizard
I know this is something to do with using computed values but i've tried reading about them and cant seem to solve this issue.
Basicly i want to use the computed value of wizardName to access an an array of that name.
Please help supports, looking forward to seeing many ways to do this!
On this line:
wizardName = [wizardName] + 'Wizard';
You are attempting to concatenate the string 'Wizard' to an Array with one string element "incident". I'm assuming you just want regular string concatenation:
wizardName = wizardName + 'Wizard';
However, now you only have a string, not an array instance. To fix that, change the way you define your *Wizard arrays to something like:
var wizardyThings = {
incidentWizard : ['page1.html','page2.html','page3.html'],
magicWizard: ['page1.html','page2.html','page3.html']
};
Then your function (which is missing a name as it stands), becomes:
function someMethod(next, wizardname) {
wizardName = wizardName + 'Wizard';
var wizSize = wizardyThings[wizardName].length;
var wizardPOS = jQuery.inArray(loadedURL, wizardyThings[wizardName]);
...
}
You can only access properties of objects that way. For global values, window[ name ] will work. For simple local variables it's just not possible at all. That is, if inside a function you've got
var something;
then there's no way to get at that variable if all you have is the string "something".
I would just put each array as a prop on an object:
var obj {
incidentWizard: ['page1.html','page2.html','page3.html'],
magicWizard: ['page1.html','page2.html','page3.html']
};
Then you can just do obj['incidentWizard'] or obj.incidentWizard this will return:
['page1.html','page2.html','page3.html']

Javascript: give a variable a name made of 2 variables

I want to create a new variable in javascript but it's name should made of a stale part and a variable one like this:
tab_counter = 1;
var editor + tab_counter = blabla
well i want the new variable name to be in this case editor1, is this possible?
You cannot create a stand-alone variable name that way (except as a global) (edit or except with eval()), but you can create an object property:
var tab_counter = 1;
var someObject = {};
someObject['editor' + tab_counter] = "bla bla";
You can create globals as "window" properties like that, but you probably shouldn't because global variables make kittens cry.
(Now, if you're really just indexing by an increasing counter, you might consider just using an array.)
edit also see #Birey's somewhat disturbing but completely correct observation that you can use "eval()" to do what you want.
It is possible
var tab_counter=1;
eval("var editor"+tab_counter+"='blah'")
alert(editor1);
eval("var editor"+tab_counter+1+";")
editor2='blahblah';
alert(editor2);
http://jsfiddle.net/5ZLYe/
You can do the eval method used by Birey or you can create a custom property of an object such as...
obj[editor + tab_counter] = blabla;
But it sounds like you're going about doing whatever you're doing in a particularly horrible way. If you just want to store multiple items which you can index into use an array...
var array = [];
array[0] = blabla;
array[1] = blabla2;
alert(array[0]); //shows value of blabla
alert(array[1]); //shows value of blabla2
It seems like you may want to consider using a Dictionary for something like this. This link which references this link describes your options there.

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