0
139
ViewsHow to join javascript array elements without forloop
I have from a mongoose query result:
{
"store": [
{
"items": [
"A1",
"A2"
]
},
{
"items": [
"A3",
"A4"
]
},
{
"items": [
"B1",
"B2"
]
},
{
"items": [
"B3",
"B4"
]
},
{
"items": [
"C8",
"C9",
"C10"
]
}
]
}
I need this: ["A1","A2","A3","A4","B1","B2","B3","B4","C8","C9",C10] Is there any way to do this without using foreach loop, as my array will be so long and it will be time consuming.
·
Juan Pablo Isaza
2 answers
Answer question0
let data = {
'store': [
{
'items': [
'A1',
'A2'
]
},
{
'items': [
'A3',
'A4'
]
},
{
'items': [
'B1',
'B2'
]
},
{
'items': [
'B3',
'B4'
]
},
{
'items': [
'C8',
'C9',
'C10'
]
}
]
}
let result = data['store'].flatMap(value => value.items)
console.log(result)
·
Juan Pablo Isaza
Report
0
To boost the performance even more you can directly use an aggregation to make use of the faster C++ performing in the database:
I am assuming your database document looks something like this:
If you use an aggregation like this:
let result = Model.aggregate([
{'$match':{'_id': "YourDesiredId"}}, // Add this line in case you want to match a specific document
{
'$unwind': {
'path': '$store'
}
}, {
'$unwind': {
'path': '$store.items'
}
}, {
'$group': {
'_id': '$_id',
'items': {
'$push': '$store.items'
}
}
}, {
'$project': {
'_id': 0
}
}
])
Your output will be:
items:["A1","A2","A3","A4","B1","B2","B3","B4","C8","C9","C10"]
·
Juan Pablo Isaza
Report
Answer question