In so many Javascript libraries and Angular plugin, I have seen the use of JS array like this:
var arr = ['size':20, 'Active', 'role':'user'];
(This is just an example how they use key and values)
I searched for javascript array but it looks different so how can we use this type of array?
Short answer: You can't write it like this because of the javascript syntax. You can still achieve this, but you shouldn't.
Long answer:
Arrays are considered as objects in Javascript. So you can do this for example :
var array = [];
array['size'] = 20;
console.log(array['size']);
It will work because the array works like any other objects. But you shouldn't do it. It will just confuse your code. Use a plain object to do that:
var obj = {'size':20, 'Active': undefined, 'role':'user'};
Related
I have the following javascript object, in an array. I am using PHP's json_encode to get this value
[ { January=100}, { February=100} ]
I am trying to convert the following objects to
["January",100],["February",100]
I have searched around a lot and couldn't find an answer.
Any help would be really appreciated. Thanks!
Assuming you're trying to do this in Javascript, it can be done very easily using a library like Lodash:
server_array.map(_.toPairs)
Using native Javascript map function, with lodash's toPairs
Ignoring the incorrect syntax of your example javascript object code...
This is how to convert a javascript object to an array:
var newArray = []
for (var i in yourObject)
if(yourObject.hasOwnProperty(i))
newArray.push([i,yourObject[i]])
The above will yield the results your looking for.
Struggling with some javascript array manipulation/updating. Hope someone could help.
I have an array:
array('saved_designs'=array());
Javascript JSON version:
{"saved_design":{}}
I will be adding a label, and associated array data:
array("saved_designs"=array('label'=array('class'='somecssclass',styles=array(ill add more assoc elements here),'hover'=array(ill add more assoc elements here))))
Javascript version:
{"saved_designs":{"label":{"class":"someclass","style":[],"hover":[]}}}
I want to be able to append/modify this array. If 'label' already defined...then cycle through the sub data for that element...and update. If 'label' doesnt exist..then append a new data set to the 'saved_designs' array element.
So, if label is not defined, add the following to the 'saved_designs' element:
array('label2' = array('class'=>'someclass2',styles=array(),'hover=>array()')
Things arent quite working out as i expect. Im unsure of the javascript notation of [], and {} and the differences.
Probably going to need to discuss this as answers are provided....but heres some code i have at the moment to achive this:
//saveLabel = label the user chose for this "design"
if(isUnique == 0){//update
//ask user if want to overwrite design styles for the specified html element
if (confirm("Their is already a design with that label ("+saveLabel+"). Overwrite this designs data for the given element/styles?")) {
currentDesigns["saved_designs"][saveLabel]["class"] = saveClass;
//edit other subdata here...
}
}else{//create new
var newDesign = [];
newDesign[saveLabel] = [];
newDesign[saveLabel]["class"] = saveClass;
newDesign[saveLabel]["style"] = [];
newDesign[saveLabel]["hover"] = [];
currentDesigns["saved_designs"].push(newDesign);//gives error..push is not defined
}
jQuery("#'.$elementId.'").val(JSON.stringify(currentDesigns));
thanks in advance. Hope this is clear. Ill update accordingly based on questions and comments.
Shaun
It can be a bit confusing. JavaScript objects look a lot like a map or a dictionary from other languages. You can iterate over them and access their properties with object['property_name'].
Thus the difference between a property and a string index doesn't really exist. That looks like php you are creating. It's called an array there, but the fact that you are identifying values by a string means it is going to be serialized into an object in javascript.
var thing = {"saved_designs":{"label":{"class":"someclass","style":[],"hover":[]}}}
thing.saved_designs.label is the same thing as thing["saved_designs"]["label"].
In javascript an array is a list that can only be accessed by integer indices. Arrays don't have explicit keys and can be defined:
var stuff = ['label', 24, anObject]
So you see the error you are getting about 'push not defined' is because you aren't working on an array as far as javascript is concerned.
currentDesigns["saved_designs"] == currentDesigns.saved_designs
When you have an object, and you want a new key/value pair (i.e. property) you don't need a special function to add. Just define the key and the value:
**currentDesigns.saved_designs['key'] = newDesign;**
If you have a different label for every design (which is what it looks like) key is that label (a string).
Also when you were defining the new design this is what javascript interprets:
var newDesign = [];
newDesign is an array. It has n number of elements accessed by integers indices.
newDesign[saveLabel] = [];
Since newDesign is a an array saveLabel should be an numerical index. The value for that index is another array.
newDesign[saveLabel]["class"] = saveClass;
newDesign[saveLabel]["style"] = [];
newDesign[saveLabel]["hover"] = [];
Here explicitly you show that you are trying to use an array as objects. Arrays do not support ['string_key']
This might very well 'work' but only because in javascript arrays are objects and there is no rule that says you can't add properties to objects at will. However all these [] are not helping you at all.
var newDesign = {label: "the label", class: saveClass};
is probably what you are looking for.
I am creating an array like the following:
var arr =[];
arr['key1'] = 'value1';
arr['key2'] = 'value2';
If is use this array in ng-repeat tag, it is not displaying anything. Is there any way to make it work?
<div data-ng-repeat='(key,value) in arr'>{{key}} - {{value}}</div>
Is there any way to make it work?
The way to go, is to creat plain object (instead of array)
// instead of creatin of an Array
// $scope.myArr = [];
// we just create plain object
$scope.myArr = {};
...
// here we just add properties (key/value)
$scope.myArr['attempt1'] = {};
...
// which is in this case same as this syntax
$scope.myArr.attempt1 = {};
Thee is updated plunker
Check more details what is behind for example here:
Javascript: Understanding Objects vs Arrays and When to Use Them. [Part 1]
Your associative array is nothing but an object, as far as JavaScript is concerned. IMO Associative arrays and Objects are almost same.
Ex: Your arr['key1'] = 'value1'; can be called as console.log(arr.key1);
To make your code work, you need to change the array declaration by removing [] and replacing with {} (Curly braces)
Like this var arr = {};
My question is the following, in an array:
var array = new Array();
array['abc'] = 'value1';
array['def'] = 'value2';
How do I get the associative key of an array if I have its index number? Let's say I want associative key of arr[0]'s associative key ( => 'abc'), or associative key of arr[1] '=> 'def'). How is this possible in jQuery?
Let's be clear, I am not looking for the value and I do not need to use $.each(). I just need to link 0 to 'abc' and 1 => 'def' etc... Unfortunately something like arr[0].assoc_key() doesn't seem to exist T_T
Thanks a bunch.
All right so the solution is pretty simple, you need to create an object which associates indeces with keys as well as keys with values. Here is a JSBin that works. Please note that to add an element, you need a custom function (addElement in this case) to be able to have both indeces and keys associated at the right places. This is a rough draft to give you an idea of how it can be done!
JSBin
If you have any question or if that wasn't exactly what you expected, simply edit your question and I'll have another glance at it. It HAS to be a custom made object if you want the behavior you asked for.
Javascript doesn't have a native Dictionary type, you would have to write it. – T McKeown
It isn't possible and jQuery doesn't come into the picture at all. If you use an array as a dictionary like that, you are doing something wrong. – Jon
rethink the way you are doing it. Maybe try array[0] = {key: 'abc', value: 'value1'} – Geezer68
#Geezer68, objects do not support multidimentional data, the array I'm working on is 3 levels deep (I know I didn't says so in my original post, but I didn't think it was relevant).
Anyway, thank you guys, it answers the question! I will rethink it then ;-)
EDIT: I guess I'll just add a level:
var array = new Array();
array[] = 'abc';
array[0] = 'value1'
I don't know an other than using a for ... in. So here how i do it and hope you get a better answer (because i want to know aswell!).
var array = new Array();
array['abc'] = 'value1';
array['def'] = 'value2';
var listKeys = [];
for(x in array) listKeys.push(x);
console.log(listKeys); // ['abc', 'def']
but using [string] on an array object is adding property to the object, not the array. So it may be better to initialise it like that :
var array = {};
You might learn more information on this technique in this question and some restriction on why you should not rely on that.
Can anyone please tell me what type of variable is this? if it is array what type of array is this? and how we can make this array from code behind.
var images = [
{ image: 'http://localhost/SocketV3/Attachments/iNAC/Temp/Post652/PPT/Slides/Slide1.png' },
{ image: 'http://localhost/SocketV3/Attachments/iNAC/Temp/Post652/PPT/Slides/Slide2.png' },
{ image: 'http://localhost/socketv3/res/i/common/icn_slideShow.png'}
];
Thanks
That is an array of objects. Simple as that.
Not to diminish the answer that is already there, but here is some further explanation.
the var images = []; is shorthand notation.
This is equivalent to var images=new Array();
Similarly,
{image:'http://localhost/SocketV3/Attachments/iNAC/Temp/Post652/PPT/Slides/Slide1.png'}
is shorthand for create an Object with one key, called image (the URL is the data). Classic notation would look more like this:
var myObj = new Object();
myObj.image = 'http://localhost/SocketV3/Attachments/iNAC/Temp/Post652/PPT/Slides/Slide1.png';
It is a simple Array of Objects...
You can use this as follows:
var first_url = images[0].image; //will give you the first URL
...
HTH
code behind screams of asp.net
if thats the case then you can use anny json libary for .net
to generate it