How to create an Auto Increment Sequence with mongoose library [closed] - javascript

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how to create an auto increment sequence with prefix, for example: USR00001 etc…
Little details: language Nodejs, and library mongoose.
Thank you.
Regards,
Michele

You can create on collection where you can keep all your sequences and then can use findAndUpdate to get them incremented automatically
collection - sequences
[
{
_id: "sequence",
"value": 100000
}
]
Then you can use this query to get the latest number in your format
db.sample.findAndModify({
query:{
_id: "sequence"
},
update: {
$inc:{
value:1
}
},
fields:{
count: {$concat: [ "USR", { $toString: "$value" } ] },
_id: 0
}
})
Output:
{ "value" : "USR100000" }
For more details you can check the official documentation of findAndUpdate

You can read this link, This has explained the way of doing it. Not sure how you will use this with Mongoose.
https://www.tutorialspoint.com/mongodb/mongodb_autoincrement_sequence.htm

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javascript array to list of array [closed]

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I have a following data, and I want to convert to list of array without key.
How do I do it?
Data
[{
"time": "01/13 15:50",
"price": 3000,
"changeRate": -0.27
},
{
"time": "01/13 15:40",
"price": 4000,
"changeRate": -0.27
}]
Desired output
[
[01/13 15:50, 3000],
[01/13 15:40, 4000]
]
Thank you in advance!
You can use the map method for that. It's used to transform (or "map") one array into a new one. The new array has the same length as the original, and its items are derived from the items in the original array.
data.map(item => [item.time, item.price]);

Removing Object from Array of Array in Javascript [closed]

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Hey Guys I am exporting some data.
And the challenge I am facing is the data should be in Array of Objects but don't know the data format is Array in Array of Objects.
I can write a script to transform the data to the desired format.
Can anyone help me out with how can I remove the object from the inner array to the outer array?
The data is in this format.
{
"data": [
[
{
"id": "4101"
}
]
]
}
My Resultant Format looks like this
Can anyone help me write a javascript to accomplish this objective
{
"data": [
{
"id": "4104",
}
]
}
Please give a try to this :
var a=obj.data.splice(0, 1);
obj.data.push(a[0]);
or in one line if you want :
obj.data.push(obj.data.splice(0, 1)[0]);
Provided you cannot correct the input at the source.

JSON jQuery auto-fill [closed]

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first of all, I really haven't learn any javascript at all, and I am stuck here.
I want to get these link in this JSON example.
"list": [
[
"List of recipes",
[
{
"name": "Eggs",
"links": [
{
"method": "Fry",
"link": "https://example.com/category/fry"
},
]
},
]
]
I can't elaborate with my friend's example code, can anyone help me?
Your JSON isn't valid so you need to fix that first.
When it's valid parse it with JSON.parse.
When it's parsed you'll have a nested array data structure. You need to access the links array by navigating through the tree with the array indexes.
// Returns an array
data.list[0]
// Get the second element of that array
// (the first element is the text "List of recipes")
// which is also an array
data.list[0][1]
// Access the first element of that array
// (an object) and return the links array
data.list[0][1][0].links
const json = '{"list":[["List of recipes",[{"name":"Eggs","links":[{"method":"Fry","link":"https://example.com/category/fry"}]}]]]}';
const data = JSON.parse(json);
console.log(data.list[0][1][0].links);

How to push() things into an array with objects [closed]

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I want to push an item into an array that in that have objects in them, like this:
var testarray = [
{
first: "See this?",
second: "Oh my!"
},
{
first: "Nice!",
second: "Amazing!"
}
]
You can see that I for this variable/array, I can't just use this testarray.push("Wonderful!"). Please show me how I can push things into these sort of arrays.
The "multiple things" are objects. Push another object in the same format.
testarray.push({first: "Wow!", second: "Wonderful!"});

how to parse array values inside object [closed]

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{ 'notes[]': [ 'book', 'copy', 'pencil', 'eraser' ] }
I just want to parse these sets. Please, anyone suggest me some best approach
Since you are using an invalid identifier as your key (notes[]), you will need to use bracket syntax to access:
var data = { 'notes[]': [ 'book', 'copy', 'pencil', 'eraser' ] };
console.log(data['notes[]']);
Probably would be better to name the key notes instead of notes[]. Then you can access with dot notation: data.notes
Maybe you want like as below code.
var res = { 'notes': [ 'book', 'copy', 'pencil', 'eraser' ] };
console.log(res.notes[0]); //=> book
console.log(res.notes[1]); //=> copy
console.log(res.notes[2]); //=> pencil
console.log(res.notes[3]); //=> eraser

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