Simple question, but I cannot find a solution.
I have an array of objects.
I also have a reference to an object from this array.
I want to delete the object from the array.
How to do it in Javascript (without comparing object properties)?
PS It is easy to do it in C# (using List collection)
List<SomeObject> list = ........ ;
SomeObject element = ......... ;
list.Remove(element);
You can use indexOf to get the index of the object and splice to remove it from the array:
var arr = [ { name: 0}, { name : 1 } , {name : 2 } ];
var myObj = arr[1];
arr.splice(arr.indexOf(myObj),1);
console.log(arr);
There is no way to do this with arrays directly. You will have to find or roll your own implementation of an collection which supports similar operation.
Related
I know this questions exists like 100 times, but I just can't transfer the solutions to my code, so I hope you can help me. This should be pretty easy but I just don't get it working.
This is just my code with other variable because of reasons:
My Code:
for (var key in array) {
}
The JSON I want:
[{
key: "One",
y: 5
}, {
key: "Two",
y: 2
},];
Pseudo JSON:
[{
key: key,
y: array[key].data
},{
key: key,
y: array[key].data;
},];
You can try this solution:
var data = [];
for (var key in array) {
data.push({
key : key,
y : array[key].data
});
}
console.log(data);
But, what about Pseudo JSON:?
DEMO - See console (chrome) for output
I don't understand what is 'array'. Is it an object or an array?
I think what you want might be this, if 'array' is an array:
var new_arr = [];
your_array.forEach( function(entry) {
new_arr.push({key: entry, y: entry.data}); // you should change it according to your need.
})
return JSON.stringify(new_arr);
Or if 'array' is just an object, you may need this:
var new_arr = [];
for (key in array) {
new_arr.push({key: key, y: array[key].data}); // you should change it according to your need.
}
return JSON.stringify(new_arr);
JSON is just a syntax for expressing objects and arrays independently of a scripting language's syntax.
Apparently you want to convert your array into another structure and have this expressed in JSON. The conversion to JSON is usually performed by the built-in function JSON.stringify.
Assuming your array isn't really an array (which has only numeric indices, usually without gaps), but more an object-like structure, I'd suggest the following code:
var data = []
for (var key in array)
{
data.push({key: key, y: array[key].data});
}
var json = JSON.stringify(data);
//...
If array really was an array you shouldn't use a for-in-loop. Otherwise you should consider renaming it to avoid confusion.
you can use following line to create an array of json
var jsonArr = [];
then you can create json object from following line
var obj = new Object();
put data in json object as following
obj['id'] = 123;
obj['name'] = 'ABC';
then put json object in json array as
jsonArr.push(obj);
you want to add multiple objects in json array then simply create json object and add one by one using push method.
[{"id":"123","name":"ABC"}]
Assuming an object is initialized as following:
var myObj = {
"key1":"val1",
"key2":"val2",
"key3":"val3",
...
};
Can I retrieve key values like this?
var retrKey1 = myObj[0];
var retrKey2 = myObj[1];
var retrKey3 = myObj[2];
...
The issue I am trying to solve is that I need to pick random key values from this object. Generating a random number is not an issue, but:
How can I retrieve the number of keys in the object/map?
Can I retrieve the key values using a integer index like in arrays?
If not, what are my options?
The Object.keys method returns an array of object properties. You can index the array with numbers then.
var myObj = {
"key1":"val1",
"key2":"val2",
"key3":"val3",
...
};
var keys = Object.keys(myObj);
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys
No, because there's no ordering among property keys. If you want ordered keys, you need to work with an array.
You could define a structure like this :
var myObj = [
{key:"key1", val:"val1"},
...
];
I'm hoping my question is using the correct terminology...
Can someone explain to me how I can perform the following:
If I have an array consisting of:
Object { id=1498, brandName="Booths", quality="Standard"}
Object { id=1499, brandName="Booths", quality="Standard"}
How can I iterate throughout that array and return another array of distinct 'keys'?
Ultimately I want an array which would return something like:
[id,brandName,quality] (but the original array is going to return different keys at different times.
Have I made sense?
You can use Object.keys:
var a1 = [{ id:1498, brandName:"Booths", quality:"Standard"},
{ id:1499, brandName:"Booths", quality:"Standard"}],
a1Keys = a1.map(function(a){return Object.keys(a);});
//a1Keys now:
[['id','brandName','quality'],['id','brandName','quality']]
The keys method is described #MDN, including a shim for older browsers
var a = {"a": 1, "b": "t" };
var keys = new Array();
for(var o in a){
keys.push(o);
}
console.log(keys)
I have data being pulled in from various sources, each returning some form of JSON or similar, although, differently formatted each time. I need to get them all into one array, but I can't figure out how to do it.
The first set is an array like this:
[
Object {id="70", type="ab", dateadded="12345678"},
Object {id="85", type="ab", dateadded="87654321"}, ... more items ...
]
The second set is being pulled in from Facebook, and is like this:
[
Object {id="12341234234", created_time="12345678"},
Object {id="567856785678", created_time="87654321"}, ... more items ...
]
So, I need to alter the second set so that it has 'type', and it has 'dateadded' instead of 'created_time', and then I need to get this all into one array so it can be sorted on 'dateadded'.
How can I do this?
Use the first array's push() method:
// for each item in second array
firstArray.push(convert(item));
function convert(obj) {
// Convert obj into format compatible with first array and return it
}
Hope this helps.
Assuming you have actual valid JSON instead of what you quoted above:
var jsonOld = '[{"id":"70","type":"ab","dateadded":"12345678"},{"id":"85","type":"ab","dateadded":"87654321"}]',
jsonNew = '[{"id":"12341234234","created_time":"12345678"},{"id":"567856785678","created_time":"87654321"}]';
Then first parse these values into actual Javascript arrays:
var mainArr = JSON.parse(jsonOld),
newArr = JSON.parse(jsonNew);
(If you already have actual Javascript arrays instead of JSON strings then skip the above step.)
Then just iterate over newArr and change the properties you need changed:
for (var i = 0, il = newArr.length; i < il; i++) {
newArr[i].type = 'ab';
newArr[i].dateadded = newArr[i].created_time;
delete newArr[i].created_time;
}
And concatenate newArr into mainArr:
mainArr = mainArr.concat(newArr);
And sort on dateadded:
mainArr.sort(function(a, b) { return a.dateadded - b.dateadded; });
This will result in:
[{"id":"70","type":"ab","dateadded":"12345678"},
{"id":"12341234234","type":"ab","dateadded":"12345678"},
{"id":"85","type":"ab","dateadded":"87654321"},
{"id":"567856785678","type":"ab","dateadded":"87654321"}]
See example
I know to add a named object to an existing JavaScript object you do this:
var json = {};
json.a = {name:"a"};
But how can you add an object to an existing JavaScript object in a similar fashion without assigning it an associative name, so that it could be accessed by a for() statement. Sorry if I'm being a little vague, I don't know a lot about JavaScript objects.
UPDATE:
I want the end result to look like this:
var json = [{name:'a'}{name:'b'}];
What you have there is not strictly a JSON object. You're using JS object literals rather.
You can do this:
var jsObj = {};
// add a 'name' property
jsObj = { name: 'a'};
var anotherObj = { other: "b" };
// will add 'other' proprty to jsObj
$.extend(jsObj, anotherObj);
// jsObj becomes - {name: 'a', other:'b'}
The JSON representation of above will look like:
var jsonString = "{'name': 'a', 'other':'b'}";
// will give you back jsObj.
var jsonObj = JSON.Parse(jsonString); // eval(jsonString) in older browsers
Note that you cannot have property without a name. This is not valid:
// invalid, will throw error
jsObj = { : 'a'};
Try an array that you push an item on to using
myArrayVar.push(value);
or
myArrayVar[myArrayVar.length] = value;
It makes no sense to have a property of an object without a property name. A "for ... in" loop is a loop over that collection of property names, after all. That is,
for (var k in obj)
will set "k" equal to each of the names of properties in "obj" in turn.
You cannot do this, because a JSON object is a collection of string-value pairs. A value can be an array, and you can push your object into that array, without an associative name.
http://www.json.org/
What you are describing is an array of objects.
var j = [{name:'a'},{name:'b'}];
This has the properties you are looking for. You can operate on it like so:
for(var i in j) {
alert(j[i].name);
}