I have this array:
const chats = [
{ id: "chat-1", msg: { text: "World", date: (a date) } },
{ id: "chat-2", msg: { text: "Hello", date: (a date) } },
];
After receiving updates from my database, I receive this object:
// The second chat with update data
{ id: "chat-2", msg: { text: "Bye", date: (a date) } },
How can I (using ES6) replace the chat object from the original chats array and move it to the first index?
For now, I am doing this, but I am looking for a fastest way (smaller O)
// Get the modified chat
const modifiedChat = response.data;
// Search the modified chat in the chats array by id
const chatIndex = chats.findIndex(
(chat) => chat.id === modifiedChat.id
);
// Finally, using spread syntax, add the updated chat to the head of our current chats array
chats = [
modifiedChat,
...chats.slice(0, chatIndex),
...chats.slice(chatIndex + 1),
];
You can do the following,
const chats = [
{ id: "chat-1", msg: { text: "World", date: '' } },
{ id: "chat-2", msg: { text: "Hello", date: '' } },
];
const modifiedChat = { id: "chat-2", msg: { text: "Bye", date: '' } };
const newChats = [modifiedChat, ...chats.filter(item => item.id !== modifiedChat.id)];
console.log(newChats);
You can do something similar to how LRU cache works. You can now access every chat in O(1)
Related
I'm writing a back code using NodeJs to fetch some data from backend, I want dataBase data to be like this
like this:
data = [{
name: "Admin",
id: '1',
children: [
{ name: "Admin", id: "1" },
{ name: "groupe1", id: "2" },
{
name: "groupe2", id: "1455", children: [
{ name: "groupe2", id: "1455" },
{ name: "gro", id: "5444" },
{ name: "hhrr", id: "45" }
]
}
]
}]
the idea is simple we have a list of group each group has a parent I want to display all the groups list in an hierarchical way the top one of the tree is done
Some groups are parents and groups in the same time and some others are only groups if the group is not parent we add an object with its name and ID in the array of children of his parent
if this groups is a parent that's mean it has children we add an object with its ID and name in the array of children of his parents, and we add property children for the object which is array named children with for the first time an object with the name and the id of the group etc...
i tryed to do this but it did not work
const getParentsByType = async ({ name, _id }) => {
let parentResult = [
{
id: _id,
name: name,
children: [
{
id: _id,
name: name,
},
],
},
];
parentResult= await findParent(_id, parentResult[0].children, 0);
return parentResult;
};
const findParent = async (parentId, parentResult, itemPos) => {
let children = await Models.GroupModel.find({ parent: parentId, status: true }).select('name _id');
for (let i = 0; i < children.length; i++) {
let childrenList = await Models.GroupModel.find({ parent: children[i]._id, status: true }).select('name _id');
if (childrenList.length != 0) {
parentResult.push(buildParentWithChild(children[i]._id, children[i].name));
findParent(children[i]._id,parentResult.children[i],itemPos++)
} else {
parentResult.push(buildParent(children[i]._id, children[i].name));
}
}
return parentResult
};
and this the model of the data base
const Group = mongoose.Schema({
name: {
type: String,
required: true,
},
status: {
type: Boolean,
required: true,
},
parent: {
type: mongoose.Schema.Types.ObjectId,
ref: 'Group',
},
});
i had two days trying to resolve tis but with no result
i need some helps and Thank you
Try parsing your returned data. It validates your data as objects i dont see any problem with your function regardless i still have no idea what format your a trying to build.
let children = JSON.parse(JSON.stringify(await Models.GroupModel.find({ parent: parentId, status: true }).select('name _id')));
let childrenList = JSON.parse(JSON.stringify(await Models.GroupModel.find({ parent: children[i]._id, status: true }).select('name _id')));
If I understand you right, you want to convert the array returned by Models.GroupModel.find, and which looks like
var dbresult = [
{_id: "1", parent: null, name: "one"},
{_id: "2", parent: "1", name: "two"}
];
into a hierarchical structure. This can be done with a function that adds all children of a given parent p, including, recursively, their children. Like the following:
function children(p) {
var result = [];
for (r of dbresult) if (r.parent === p) {
var row = {_id: r._id, name: r.name};
var chld = children(r._id);
if (chld.length > 0) row.children = chld;
result.push(row);
}
return result;
}
console.log(JSON.stringify(children(null)));
Note that this approach requires only one database access (to fill the dbresult) and is therefore probably faster than your findParent function.
I can't google the right solution for this for about an hour straight,
So I'm getting a response from the API that looks like this:
[
{
"Name": "name1",
"Title": "Name One",
"Children": [
{
"Name": "Name 1.1",
"Title": "Name one point one"
},
]
And I need it to fit this kind of "mold" for the data to fit in:
{
title: 'Name One',
value: 'name1',
key: '1',
children: [
{
title: 'Name one point one',
value: 'Name 1.1',
key: 'key1',
},
I am trying to achieve this using a foreach but It's not working as intended because I need to do this all in one instance of a foreach.
Here's what I gave a go to(vue2):
created() {
getData().then(response => {
const formattedResponse = []
response.forEach((el, key) => {
formattedResponse.title = response.Title
formattedResponse.name = response.Name
formattedResponse.children = response.Children
})
})
Use map over the main array and use destructuring assignment to extract the properties by key, and relabel them, and then do exactly the same with the children array. Then return the updated array of objects.
const data=[{Name:"name1",Title:"Name One",Children:[{Name:"Name 1.1",Title:"Name one point one"}]},{Name:"name2",Title:"Name Two",Children:[{Name:"Name 1.2",Title:"Name one point two"}]}];
const result = data.map((obj, key) => {
const { Title: title, Name: value } = obj;
const children = obj.Children.map(obj => {
const { Title: title, Name: value } = obj;
return { title, value, key: (key + 1).toString() };
});
return { title, value, children };
});
console.log(result);
Your API response is JSON. All you need to do is:
var resp=JSON.parse(API response);
I currenty have an array of dates that looks like the following:
[
"2021-05-01",
"2021-05-02",
"2021-05-03",
]
In a separate entry array, I have entries that contain the dates that pertain to a specific date:
[
{
id: 5e24d1fa-aa66-4122-b1eb-97792f0893b0,
name: "Rodriquez Family",
selectedDates: ["2021-05-01"],
status: "submitted"
},
{
id: 269a0381-63c7-4ab6-92d8-7f7b836aee6f,
name: "Test Family",
selectedDates: ["2021-05-03"],
status: "submitted"
}
]
I am attempting to pair the two arrays for a result that would look something like the following:
[
{
date: "2021-05-01",
event: {
id: 5e24d1fa-aa66-4122-b1eb-97792f0893b0,
name: "Rodriquez Family",
selectedDates: ["2021-05-01"],
status: "submitted"
}
},
{
date: "2021-05-02",
event: null
},
{
date: "2021-05-03",
event: {
id: 269a0381-63c7-4ab6-92d8-7f7b836aee6f,
name: "Test Family",
selectedDates: ["2021-05-03"],
status: "submitted"
}
]
The issue I am running into is that as I loop through the events array and check if an event has a selected date that belongs to to a date in the dates array. It duplicates the dates for however many events there are. My function looks like the following:
const getDates = async () => {
const addEvents = dateArr.map((date) => {
return events.map((event) => {
if (event.selectedDates.includes(date)) {
return { date, event };
}
return { date, event: null, checked: false };
});
});
console.log(addEvents.flat());
};
I have included a condesandbox using react for debugging!! https://codesandbox.io/s/dawn-snow-03r59?file=/src/App.js The code sandbox will show how the dates are being duplicated.
For each dateArr element, you're iterating over events and returning a list of objects with the two specified options. Instead, you can use Array#find to check if it exists or not:
const
dateArr = ["2021-05-01", "2021-05-02", "2021-05-03"],
events = [
{ id: "5e24d1fa-aa66-4122-b1eb-97792f0893b0", name: "Rodriquez Family", selectedDates: ["2021-05-01"], status: "submitted" },
{ id: "269a0381-63c7-4ab6-92d8-7f7b836aee6f", name: "Test Family", selectedDates: ["2021-05-03"], status: "submitted" }
];
const list = dateArr.map(date => {
const event = events.find(({ selectedDates = [] }) => selectedDates.includes(date));
return event ? { date, event } : { date, event: null, checked: false };
});
console.log(list);
I have this data
var data = [
{
title: "App development summary",
category: [],
},
{
title: "to experiment 2",
category: [],
},
{
title: "Some of these books I have read",
category: [
{
_id: "5f7c99faab20d14196f2062e",
name: "books",
},
{
_id: "5f7c99faab20d14196f2062f",
name: "to read",
},
],
},
{
title: "Quora users and snippets",
category: [
{
_id: "5f7c99feab20d14196f20631",
name: "quora",
},
],
},
{
title: "Politics to research",
category: [
{
_id: "5f7c9a02ab20d14196f20633",
name: "politics",
},
],
},
];
Say I want to get all the entries with the category of books. I tried doing this:
var bookCat = data.map(note => {
return note.category.map(cat => {
if(cat.name === "books" ) return note
})
})
But the result comes back with some empty and undefined arrays.
I was able to filter the empty arrays (at one point) but not the undefined
Edit
In plain English "if the object ha category.name "books", give me the title"
Filter by whether the array's category contains at least one name which is books:
var data=[{title:"App development summary",category:[]},{title:"to experiment 2",category:[]},{title:"Some of these books I have read",category:[{_id:"5f7c99faab20d14196f2062e",name:"books"},{_id:"5f7c99faab20d14196f2062f",name:"to read"}]},{title:"Quora users and snippets",category:[{_id:"5f7c99feab20d14196f20631",name:"quora"}]},{title:"Politics to research",category:[{_id:"5f7c9a02ab20d14196f20633",name:"politics"}]}];
const output = data
.filter(item => item.category.some(
({ name }) => name === 'books'
));
console.log(output);
If there's guaranteed to be only a single matching object, use .find instead:
var data=[{title:"App development summary",category:[]},{title:"to experiment 2",category:[]},{title:"Some of these books I have read",category:[{_id:"5f7c99faab20d14196f2062e",name:"books"},{_id:"5f7c99faab20d14196f2062f",name:"to read"}]},{title:"Quora users and snippets",category:[{_id:"5f7c99feab20d14196f20631",name:"quora"}]},{title:"Politics to research",category:[{_id:"5f7c9a02ab20d14196f20633",name:"politics"}]}];
const output = data
.find(item => item.category.some(
({ name }) => name === 'books'
));
console.log(output);
I have an array in my state :
projects: [
{ title: 'todo 1', person: 'Sam', status: 'ongoing'},
{ title: 'project', person: 'Jack', status: 'complete' },
{ title: 'Design video', person: 'Tim', status: 'complete' },
{ title: 'Create a forum', person: 'Jade', status: 'overdue' },
{ title: 'application', person: 'Jade', status: 'ongoing'},],
From this array (projects), I would like to generate a new array with Javascript and to get this result :
totalByPersonAndStatus : [
{person : 'Sam', complete: 0, ongoing: 1, overdue: 0 },
{person : 'Jack', complete: 1, ongoing: 0, overdue: 0 },
{person : 'Tim', complete: 1, ongoing: 0, overdue: 0 },
{person : 'Jade', complete: 0, ongoing: 1, overdue: 1 },]
I tried it
totalProjectsByPersonAndStatus: state => {
state.projects.forEach(name => {
state. totalByPersonAndStatus["name"] = name.person;
});
return state. totalByPersonAndStatus;
The problem, if a make a console.log(this.totalByPersonAndStatus) I have an object with only the data of projects.name [name: "Jade", __ob__: Observer]
Can you help me ?
Thank you
You can use reduce
let projects =[{title:'todo1',person:'Sam',status:'ongoing'},{title:'project',person:'Jack',status:'complete'},{title:'Designvideo',person:'Tim',status:'complete'},{title:'Createaforum',person:'Jade',status:'overdue'},{title:'application',person:'Jade',status:'ongoing'},]
let desired = projects.reduce((output,{person,status}) => {
if( output[person] ){
output[person][status]++
} else {
output[person] = {
person,
complete: Number(status==='complete'),
ongoing: Number(status==='ongoing'),
overdue: Number(status==='overdue')
}
}
return output;
},{})
console.log(Object.values(desired))
Create a new Set for people and statuses by iterating through the projects, a set has only unique values so sets are a convenience, iterate through your people set creating a new object with all the statuses initialized to 0, then iterate over the projects to increment the various statuses that apply. This method allows any number of new statuses to be added without changing the code - dynamic.
var people = new Set();
var status = new Set();
projects.forEach((p)=>{
people.add(p.person);
status.add(p.status);
});
var totalByPersonAndStatus = [];
people.forEach((person)=>{
let peeps = { "person": person };
status.forEach((stat)=>{
peeps[stat] = 0;
});
projects.forEach((project)=>{
if (project.person === person) { peeps[project.status]++; }
});
totalByPersonAndStatus.push(peeps);
});
You could use reduce and destructuring like this:
const projects=[{title:'todo 1',person:'Sam',status:'ongoing'},{title:'project',person:'Jack',status:'complete'},{title:'Design video',person:'Tim',status:'complete'},{title:'Create a forum',person:'Jade',status:'overdue'},{title:'application',person:'Jade',status:'ongoing'}]
const merged = projects.reduce((acc,{person,status})=>{
acc[person] = acc[person] || { person, ongoing:0, complete:0, overdue:0}
acc[person][status]++;
return acc;
},{})
console.log(Object.values(merged))
The goal is create an object merged with each person as key and then increment based on the statuses:
{
"Sam": {
"person": "Sam",
"ongoing": 1,
"complete": 0,
"overdue": 0
},
"Jack": {
}
...
}
Then use Object.values, to get the final array.
You could make it a one-liner:
const projects=[{title:'todo 1',person:'Sam',status:'ongoing'},{title:'project',person:'Jack',status:'complete'},{title:'Design video',person:'Tim',status:'complete'},{title:'Create a forum',person:'Jade',status:'overdue'},{title:'application',person:'Jade',status:'ongoing'}],
output = Object.values(projects.reduce((a,{person,status})=>
((a[person] = a[person] || {person,ongoing:0,complete:0,overdue:0})[status]++,a),{}))
console.log(output)