Develop Reference

Insert element inside array

I have a function
checkName(output) {
output.filter((NewData) => {
return this.props.elements.filter((OldData) => {
if (NewData.key == OldData.key) {
NewData.name = OldData.name,
//there i need to add another element
// Need to add newData.number = OldData.number
}
return NewData
})
})
return output
}
and I call this function like:
const named = this.checkName(product.rows)
Now I need to add to my product's array that I passed to checkName the value "OldData.Number" to "newData.Number" that is not defined in product (so I need to create this field)
For example:
Product before the checkName function
product.rows = [NewData.name]
Product after the checkName function
product.rows = [NewData.name="value of OldData.name", NewData.number="value of OldData.number"]
How can I obtain this result?

There are 2 confusing things in your code:
You are using filter to execute an action in each member of the output array. However, filter should be used to... well, filter that array, meaning that is should not modify it, just return a sub-set of it. Instead, you might want to use forEach. However, taking into accound the next bullet, probably you want to use map.
You are modifying the array passed to the checkName function. This is confusing and can lead to hard-to-find bugs. Instead, make your function "pure", meaning that it should not mutate its inputs, instead just return the data you need from it.
I would suggest some implementation like this one:
checkName(output){
return output.map((NewData) => {
// find the old data item corresponding to the current NewData
const OldData = this.props.elements.find(x => x.key === NewData.key);
if (OldData) {
// If found, return a clone of the new data with the old data name
// This uses the spread syntax: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax
return {
...NewData, // Clone the NewData object
name: OldData.name, // set the value found in OldData.name in the "name" field of the cloned object
number: OldData.number, // You can do the same for each field for which you want to replace the value cloned from NewValue
};
} else {
// Otherwise, just return a clone of the NewData
return { ...NewData };
}
}
}
The usage would be like this:
const named = this.checkName(product.rows)
Be aware that the product.rows array won't be modified!

You can get keys and values of the old object.
const keys = Object.keys(oldObject);
const values = Object.values(oldObject);
// or
const [keys, values] = Object.entries(oldObject);
After, you will create a loop with all keys of oldObject, and insert in newObject like a array.
keys.forEach( (key, index) => newObject[key] = values[index]);
// or
for (const [key, value] of Object.entries(object1)) {
newObject[key] = value
}

Use map like this.
checkName(output){
return output.map(( NewData) =>{
this.props.elements.forEach((OldData) => {
if (NewData.key == OldData.key) {
NewData.name = OldData.name;
NewData.number = OldData.number;
}
})
return NewData;
})
// return output;
}

Check if key exist

I have groupedTags and I need to add fields to it and add new tags across field.:
let groupedTags = {
'other': {}
}
if (!groupedTags.other[field]) {
groupedTags.other[field] = [];
}
groupedTags.other[field].push(tag);
I understand that it is necessary to initialize a new field to push new tag - Is there a more beautiful way to check if a field exists every time? I mean avoid explicit check. or is there nothing terrible about this check? there are just a lot of places where it can be repeated

Maybe you should investigate using Proxies for achieving your desired result.
Here's short example of doing so CodeSandbox -example
1) Create proxy handler to customise Object behaviour
const handler = {
set: function(obj, key, value) {
if (!obj[key]) {
obj[key] = [];
}
obj[key].push(value);
return true;
}
};
2) Assign Proxy to your Object
let groupedTags = {
other: new Proxy({}, handler)
};
Now assigning new value will go trough Proxy
groupedTags.other.b = "bar";
// {"other":{"b":["bar"]}}

If you want to create an array of elements on an empty (or not) object, you can try this. So you don't have to check if the property you want to push your element(s) already exists.
If it doesn't it will concat with an empty array, giving you an array with the one element, otherwise the value will be added to that array. Hope this helps.
const o = {};
const toAdd = [1,2,3,4];
toAdd.forEach((v) => {
o.other = (o.other || []).concat(v);
});
o.other2 = (o.other2 || []).concat(123);
console.log(o);

I believe there is no way around checking for a value + if needed initalizing it, other than doing it yourself explicitly.
You can take out one occurrence of groupedTags.other[field] using || like this:
let field = "foo", tag = "bar";
let groupedTags = {
'other': {}
}
// Get the existing items, or assign a new list & use it:
var items = groupedTags.other[field] || (groupedTags.other[field] = []);
items.push(tag);
console.log(groupedTags);
You could also make use of a helper method that encapsulates the check-and-init part:
let groupedTags = {
'other': {}
}
AddTag(groupedTags.other, "foo1", "bar1");
AddTag(groupedTags.other, "foo2", "bar2a");
AddTag(groupedTags.other, "foo2", "bar2b");
console.log(groupedTags);
// Can put this in a library.js
function AddTag(obj, field, tag) {
var items = obj[field] || (obj[field] = []);
items.push(tag);
}

Remove an object's key and value using a variable from function

Hey I'm trying to remove a key:value pair from state inside a Javascript Object.
It works when I hardcode the key name in the code, but when I try to use a variable from a function call, it does nothing.
Can somebody help me out?
Here's an object example:
toppingsSelected: {
"Onion":"true",
"Mushrooms":"true",
}
This works, hardcoded:
deleteTopping = toppingName => {
const { Onion, ...withoutOnion } = toppingsSelected;
console.log(withoutOnion); // Returns object without onion
};
This doesn't work:
deleteTopping = toppingName => {
const toppingName = "Onion"; // Variable gets passed in
const { toppingName, ...withoutOnion } = toppingsSelected;
console.log(withoutOnion); // Returns original object, no change made
};
So I'm basically trying to remove a key from React state but I'm pretty new to Javascript.
How can I make Javascript aware that toppingName is a key?

Another option is to add square brackets arround toppingName, and assign it to a variable. As #Bergi pointed out in the comments, this option does not mutate toppingsSelected
const toppingsSelected = {
"Onion":"true",
"Mushrooms":"true",
};
const toppingName = "Onion";
const {
[toppingName]: topping,
...withoutOnion
} = toppingsSelected;
console.log(JSON.stringify(withoutOnion));
To set the React state, you'd then do this
this.setState({ toppingsSelected: withoutOnion })

You can use delete e.g.
delete toppingsSelected[toppingName];

One way of doing this is using Array.prototype.filter()
const _obj = {
'Onion': true,
'notOnion': false
};
const newObj = Object.keys(_obj)
.filter(key => key !== 'Onion')
.reduce((acc, cur) => ({ ...acc, cur }), {})
console.log(newObj); // { notOnion: false }
This will return a new object without the 'Onion' property

How to access element in returned object using javascript?

I've been given a socket which returns me an object.
And i'd like to access one of its values, however I don't know how to.
What i need is a "balance" value for every object.
Down below there is a screenshot from my console.
Thanks for the help in advance

On both cases you need to access the properties by [] notation.
1) You can do it in for in loop
var obj = /**/; //Your object
for(key in obj.message){
if(obj.message.hasOwnProperty(key)){
obj.message[key].balance <- use this syntax to get the balance of each item
}
}
2) Or via Object.keys()
var obj = {
message:{
item1:{
balance: 1000
},
item2:{
balance: 2000
}
}
};
Object.keys(obj.message).forEach(key => console.log(obj.message[key].balance));

ObjectName.message.forEach(item,index){
console.log(item.message);
}
You can either iterate over the hashs only and get the message value.
Use object name instead of ObjectName on code.

well, let say you now keep your object in a variable called my_obj, then do following:
if (my_obj.hasOwnProperty('message')) {
for(key in my_obj.message){
if ((typeof my_obj.message[key] == 'object') && (my_obj.message[key].hasOwnProperty('balance'))) {
var balance = my_obj.message[key].balance;
// Now do something what you need
}
}
}

Ok thanks to you, I've menaged to pull it off.
Down below there is a working code :)
var objcts = $.each(msg.message, function () {});
for (key in objcts) {
if (objcts.hasOwnProperty(key)) {
var balance = objcts[key].balance;
console.log(balance);
}
}

Editing a jagged array in Javascript

I wish to simulate a taskbar (of running tasks/apps). I plan to store tasks something like this:
(function ()
{
var tasks = [];
addTask = function (taskName, taskWindow)
{
if (!tasks[taskName]) { tasks[taskName] = []; }
tasks[taskName].push({ taskWindow: taskWindow, taskName: taskName});
};
removeTask = function (taskName, taskWindow)
{
if (tasks[taskName])
{
//Somehow remove the object from the array
}
};
}());
How should I write removeTask() to remove the correct element from this jagged array?

I suggest using object to store your tasks, because it will make your ( specific to your requirement, I am not talking about Array vs Object) code cleaner and easier to maintain
var taskManager = (function(){
function taskManager(tasks){
// Do your tasks validation before passing to this.
var this.tasks = tasks || {}; // tasks value is not private here
}
// Assuming taskID would be unique value
taskManager.prototype.addTask = function (taskName, taskID){
if ( !this.tasks[taskID] ) {
this.tasks[taskID] = { taskID: taskID, taskName: taskName };
}
};
taskManager.prototype.removeTask = function (taskName, taskID){
if (this.tasks[taskID]){
delete this.tasks[taskID];
}
};
return taskManager;
})();
Usage:
var taskManager1 = new taskManager();
taskManager1.addTask(a,b);
taskManager1.removeTask(a);

Arrays are meant to have numeric indexes and you can use .splice() to remove a numeric indexed item from an array. Non-numeric indexes aren't really in the array, they end up just being properties on the array object and they can be removed with the delete operator.
If you don't have numeric indexes, then you should be using an object and use a property to index each item. When doing it that way, you can use delete tasks[taskName] to remove a property from the object.