How to merge and return new array from object in es6 The 2019 Stack Overflow Developer Survey Results Are In Announcing the arrival of Valued Associate #679: Cesar Manara Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern) The Ask Question Wizard is Live! Data science time! April 2019 and salary with experienceHow can I merge properties of two JavaScript objects dynamically?How do I remove a property from a JavaScript object?How do I check if an array includes an object in JavaScript?How to append something to an array?How to insert an item into an array at a specific index (JavaScript)?How do I correctly clone a JavaScript object?Sort array of objects by string property valueHow to check if an object is an array?How do I remove a particular element from an array in JavaScript?How do I return the response from an asynchronous call?
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How to merge and return new array from object in es6
The 2019 Stack Overflow Developer Survey Results Are In
Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)
The Ask Question Wizard is Live!
Data science time! April 2019 and salary with experienceHow can I merge properties of two JavaScript objects dynamically?How do I remove a property from a JavaScript object?How do I check if an array includes an object in JavaScript?How to append something to an array?How to insert an item into an array at a specific index (JavaScript)?How do I correctly clone a JavaScript object?Sort array of objects by string property valueHow to check if an object is an array?How do I remove a particular element from an array in JavaScript?How do I return the response from an asynchronous call?
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Suppose there are two objects.
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
and the result
'1-1':[
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
],
'1-2':[
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
],
'2-1':[
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212' ,
]
Basically, I want to group the data.
I use includes
to check if the item from b
to match the id from a
. Then construct the new array.
This is my attempt(fiddle):
return b.map(item => a.map(jtem =>
if(jtem.id.includes(item))
return
[item]: jtem
))
For somehow, it doesn't work.
and, is there a clever way to avoid the nested for
loop or map
function?
javascript ecmascript-6 ecmascript-7
add a comment |
Suppose there are two objects.
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
and the result
'1-1':[
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
],
'1-2':[
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
],
'2-1':[
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212' ,
]
Basically, I want to group the data.
I use includes
to check if the item from b
to match the id from a
. Then construct the new array.
This is my attempt(fiddle):
return b.map(item => a.map(jtem =>
if(jtem.id.includes(item))
return
[item]: jtem
))
For somehow, it doesn't work.
and, is there a clever way to avoid the nested for
loop or map
function?
javascript ecmascript-6 ecmascript-7
Shouldn't the result be an object?
– Jack Bashford
Mar 25 at 7:02
@JackBashford Hey man, sry, u r right, I just updated it.
– SPG
Mar 25 at 7:08
Do you really wantincludes
? I'd recommendstartsWith
– Bergi
Mar 25 at 8:26
@Bergi thx, I thinkstartWith
is better
– SPG
Mar 26 at 0:30
add a comment |
Suppose there are two objects.
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
and the result
'1-1':[
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
],
'1-2':[
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
],
'2-1':[
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212' ,
]
Basically, I want to group the data.
I use includes
to check if the item from b
to match the id from a
. Then construct the new array.
This is my attempt(fiddle):
return b.map(item => a.map(jtem =>
if(jtem.id.includes(item))
return
[item]: jtem
))
For somehow, it doesn't work.
and, is there a clever way to avoid the nested for
loop or map
function?
javascript ecmascript-6 ecmascript-7
Suppose there are two objects.
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
and the result
'1-1':[
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
],
'1-2':[
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
],
'2-1':[
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212' ,
]
Basically, I want to group the data.
I use includes
to check if the item from b
to match the id from a
. Then construct the new array.
This is my attempt(fiddle):
return b.map(item => a.map(jtem =>
if(jtem.id.includes(item))
return
[item]: jtem
))
For somehow, it doesn't work.
and, is there a clever way to avoid the nested for
loop or map
function?
javascript ecmascript-6 ecmascript-7
javascript ecmascript-6 ecmascript-7
edited Mar 25 at 7:04
SPG
asked Mar 25 at 7:01
SPGSPG
2,452103359
2,452103359
Shouldn't the result be an object?
– Jack Bashford
Mar 25 at 7:02
@JackBashford Hey man, sry, u r right, I just updated it.
– SPG
Mar 25 at 7:08
Do you really wantincludes
? I'd recommendstartsWith
– Bergi
Mar 25 at 8:26
@Bergi thx, I thinkstartWith
is better
– SPG
Mar 26 at 0:30
add a comment |
Shouldn't the result be an object?
– Jack Bashford
Mar 25 at 7:02
@JackBashford Hey man, sry, u r right, I just updated it.
– SPG
Mar 25 at 7:08
Do you really wantincludes
? I'd recommendstartsWith
– Bergi
Mar 25 at 8:26
@Bergi thx, I thinkstartWith
is better
– SPG
Mar 26 at 0:30
Shouldn't the result be an object?
– Jack Bashford
Mar 25 at 7:02
Shouldn't the result be an object?
– Jack Bashford
Mar 25 at 7:02
@JackBashford Hey man, sry, u r right, I just updated it.
– SPG
Mar 25 at 7:08
@JackBashford Hey man, sry, u r right, I just updated it.
– SPG
Mar 25 at 7:08
Do you really want
includes
? I'd recommend startsWith
– Bergi
Mar 25 at 8:26
Do you really want
includes
? I'd recommend startsWith
– Bergi
Mar 25 at 8:26
@Bergi thx, I think
startWith
is better– SPG
Mar 26 at 0:30
@Bergi thx, I think
startWith
is better– SPG
Mar 26 at 0:30
add a comment |
1 Answer
1
active
oldest
votes
You can do that in following steps:
Apply
reduce()
on the arrayb
During each iteration use
filter()
on the the arraya
- Get all the items from
a
which starts with item ofb
usingString.prototype.startsWith()
- At last set it as property of the
ac
and returnac
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = b.reduce((ac,b) =>
ac[b] = a.filter(x => x.id.startsWith(b));
return ac;
,)
console.log(res)
As suggested by @Falco is the comments that It would be better to scan over the a
once as its large. So here is that version.Actually its better regarding performance
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = a.reduce((ac,x) =>
let temp = b.find(y => x.id.startsWith(y))
if(!ac[temp]) ac[temp] = [];
ac[temp].push(x);
return ac;
,)
console.log(res)
Note: startsWith
is not supported by I.E. So you can create polyfill using indexOf
if(!String.prototype.startWith)
String.prototype.startsWith = function(str)
return this.indexOf(str) === 0
1
While it is specifically said in the question that the op wants to use es6, and that IE don't support es6 features, I just want to mention that startsWith() don't work in IE (while reduce, filter, and setting a property of an object is totally fine if IE > 9) and if someone wants to do the same thing that startsWith do, they can implment their own with some substring :)
– Neyt
Mar 25 at 10:07
For biga
and smallb
I would probably go witha.reduce(...)
because of locality and only scan over the big array once.
– Falco
Mar 25 at 11:13
@Falco Thanks for suggestion I updated.
– Maheer Ali
Mar 25 at 11:30
1
@Neyt Thanks for suggestion I updated
– Maheer Ali
Mar 25 at 11:33
@MaheerAli Thank you - here is a benchmark comparing the two :-) jsbench.me/dfjtoadysr/1
– Falco
Mar 25 at 11:47
add a comment |
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1 Answer
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active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
You can do that in following steps:
Apply
reduce()
on the arrayb
During each iteration use
filter()
on the the arraya
- Get all the items from
a
which starts with item ofb
usingString.prototype.startsWith()
- At last set it as property of the
ac
and returnac
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = b.reduce((ac,b) =>
ac[b] = a.filter(x => x.id.startsWith(b));
return ac;
,)
console.log(res)
As suggested by @Falco is the comments that It would be better to scan over the a
once as its large. So here is that version.Actually its better regarding performance
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = a.reduce((ac,x) =>
let temp = b.find(y => x.id.startsWith(y))
if(!ac[temp]) ac[temp] = [];
ac[temp].push(x);
return ac;
,)
console.log(res)
Note: startsWith
is not supported by I.E. So you can create polyfill using indexOf
if(!String.prototype.startWith)
String.prototype.startsWith = function(str)
return this.indexOf(str) === 0
1
While it is specifically said in the question that the op wants to use es6, and that IE don't support es6 features, I just want to mention that startsWith() don't work in IE (while reduce, filter, and setting a property of an object is totally fine if IE > 9) and if someone wants to do the same thing that startsWith do, they can implment their own with some substring :)
– Neyt
Mar 25 at 10:07
For biga
and smallb
I would probably go witha.reduce(...)
because of locality and only scan over the big array once.
– Falco
Mar 25 at 11:13
@Falco Thanks for suggestion I updated.
– Maheer Ali
Mar 25 at 11:30
1
@Neyt Thanks for suggestion I updated
– Maheer Ali
Mar 25 at 11:33
@MaheerAli Thank you - here is a benchmark comparing the two :-) jsbench.me/dfjtoadysr/1
– Falco
Mar 25 at 11:47
add a comment |
You can do that in following steps:
Apply
reduce()
on the arrayb
During each iteration use
filter()
on the the arraya
- Get all the items from
a
which starts with item ofb
usingString.prototype.startsWith()
- At last set it as property of the
ac
and returnac
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = b.reduce((ac,b) =>
ac[b] = a.filter(x => x.id.startsWith(b));
return ac;
,)
console.log(res)
As suggested by @Falco is the comments that It would be better to scan over the a
once as its large. So here is that version.Actually its better regarding performance
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = a.reduce((ac,x) =>
let temp = b.find(y => x.id.startsWith(y))
if(!ac[temp]) ac[temp] = [];
ac[temp].push(x);
return ac;
,)
console.log(res)
Note: startsWith
is not supported by I.E. So you can create polyfill using indexOf
if(!String.prototype.startWith)
String.prototype.startsWith = function(str)
return this.indexOf(str) === 0
1
While it is specifically said in the question that the op wants to use es6, and that IE don't support es6 features, I just want to mention that startsWith() don't work in IE (while reduce, filter, and setting a property of an object is totally fine if IE > 9) and if someone wants to do the same thing that startsWith do, they can implment their own with some substring :)
– Neyt
Mar 25 at 10:07
For biga
and smallb
I would probably go witha.reduce(...)
because of locality and only scan over the big array once.
– Falco
Mar 25 at 11:13
@Falco Thanks for suggestion I updated.
– Maheer Ali
Mar 25 at 11:30
1
@Neyt Thanks for suggestion I updated
– Maheer Ali
Mar 25 at 11:33
@MaheerAli Thank you - here is a benchmark comparing the two :-) jsbench.me/dfjtoadysr/1
– Falco
Mar 25 at 11:47
add a comment |
You can do that in following steps:
Apply
reduce()
on the arrayb
During each iteration use
filter()
on the the arraya
- Get all the items from
a
which starts with item ofb
usingString.prototype.startsWith()
- At last set it as property of the
ac
and returnac
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = b.reduce((ac,b) =>
ac[b] = a.filter(x => x.id.startsWith(b));
return ac;
,)
console.log(res)
As suggested by @Falco is the comments that It would be better to scan over the a
once as its large. So here is that version.Actually its better regarding performance
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = a.reduce((ac,x) =>
let temp = b.find(y => x.id.startsWith(y))
if(!ac[temp]) ac[temp] = [];
ac[temp].push(x);
return ac;
,)
console.log(res)
Note: startsWith
is not supported by I.E. So you can create polyfill using indexOf
if(!String.prototype.startWith)
String.prototype.startsWith = function(str)
return this.indexOf(str) === 0
You can do that in following steps:
Apply
reduce()
on the arrayb
During each iteration use
filter()
on the the arraya
- Get all the items from
a
which starts with item ofb
usingString.prototype.startsWith()
- At last set it as property of the
ac
and returnac
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = b.reduce((ac,b) =>
ac[b] = a.filter(x => x.id.startsWith(b));
return ac;
,)
console.log(res)
As suggested by @Falco is the comments that It would be better to scan over the a
once as its large. So here is that version.Actually its better regarding performance
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = a.reduce((ac,x) =>
let temp = b.find(y => x.id.startsWith(y))
if(!ac[temp]) ac[temp] = [];
ac[temp].push(x);
return ac;
,)
console.log(res)
Note: startsWith
is not supported by I.E. So you can create polyfill using indexOf
if(!String.prototype.startWith)
String.prototype.startsWith = function(str)
return this.indexOf(str) === 0
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = b.reduce((ac,b) =>
ac[b] = a.filter(x => x.id.startsWith(b));
return ac;
,)
console.log(res)
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = b.reduce((ac,b) =>
ac[b] = a.filter(x => x.id.startsWith(b));
return ac;
,)
console.log(res)
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = a.reduce((ac,x) =>
let temp = b.find(y => x.id.startsWith(y))
if(!ac[temp]) ac[temp] = [];
ac[temp].push(x);
return ac;
,)
console.log(res)
const a = [
id: '1-1-1', name: 'a111' ,
id: '1-1-2', name: 'a112' ,
id: '1-2-1', name: 'a121' ,
id: '1-2-2', name: 'a122' ,
id: '2-1-1', name: 'a211' ,
id: '2-1-2', name: 'a212'
]
const b = ['1-1', '1-2', '2-1']
let res = a.reduce((ac,x) =>
let temp = b.find(y => x.id.startsWith(y))
if(!ac[temp]) ac[temp] = [];
ac[temp].push(x);
return ac;
,)
console.log(res)
if(!String.prototype.startWith)
String.prototype.startsWith = function(str)
return this.indexOf(str) === 0
if(!String.prototype.startWith)
String.prototype.startsWith = function(str)
return this.indexOf(str) === 0
edited Mar 25 at 15:19
answered Mar 25 at 7:04
Maheer AliMaheer Ali
10.6k825
10.6k825
1
While it is specifically said in the question that the op wants to use es6, and that IE don't support es6 features, I just want to mention that startsWith() don't work in IE (while reduce, filter, and setting a property of an object is totally fine if IE > 9) and if someone wants to do the same thing that startsWith do, they can implment their own with some substring :)
– Neyt
Mar 25 at 10:07
For biga
and smallb
I would probably go witha.reduce(...)
because of locality and only scan over the big array once.
– Falco
Mar 25 at 11:13
@Falco Thanks for suggestion I updated.
– Maheer Ali
Mar 25 at 11:30
1
@Neyt Thanks for suggestion I updated
– Maheer Ali
Mar 25 at 11:33
@MaheerAli Thank you - here is a benchmark comparing the two :-) jsbench.me/dfjtoadysr/1
– Falco
Mar 25 at 11:47
add a comment |
1
While it is specifically said in the question that the op wants to use es6, and that IE don't support es6 features, I just want to mention that startsWith() don't work in IE (while reduce, filter, and setting a property of an object is totally fine if IE > 9) and if someone wants to do the same thing that startsWith do, they can implment their own with some substring :)
– Neyt
Mar 25 at 10:07
For biga
and smallb
I would probably go witha.reduce(...)
because of locality and only scan over the big array once.
– Falco
Mar 25 at 11:13
@Falco Thanks for suggestion I updated.
– Maheer Ali
Mar 25 at 11:30
1
@Neyt Thanks for suggestion I updated
– Maheer Ali
Mar 25 at 11:33
@MaheerAli Thank you - here is a benchmark comparing the two :-) jsbench.me/dfjtoadysr/1
– Falco
Mar 25 at 11:47
1
1
While it is specifically said in the question that the op wants to use es6, and that IE don't support es6 features, I just want to mention that startsWith() don't work in IE (while reduce, filter, and setting a property of an object is totally fine if IE > 9) and if someone wants to do the same thing that startsWith do, they can implment their own with some substring :)
– Neyt
Mar 25 at 10:07
While it is specifically said in the question that the op wants to use es6, and that IE don't support es6 features, I just want to mention that startsWith() don't work in IE (while reduce, filter, and setting a property of an object is totally fine if IE > 9) and if someone wants to do the same thing that startsWith do, they can implment their own with some substring :)
– Neyt
Mar 25 at 10:07
For big
a
and small b
I would probably go with a.reduce(...)
because of locality and only scan over the big array once.– Falco
Mar 25 at 11:13
For big
a
and small b
I would probably go with a.reduce(...)
because of locality and only scan over the big array once.– Falco
Mar 25 at 11:13
@Falco Thanks for suggestion I updated.
– Maheer Ali
Mar 25 at 11:30
@Falco Thanks for suggestion I updated.
– Maheer Ali
Mar 25 at 11:30
1
1
@Neyt Thanks for suggestion I updated
– Maheer Ali
Mar 25 at 11:33
@Neyt Thanks for suggestion I updated
– Maheer Ali
Mar 25 at 11:33
@MaheerAli Thank you - here is a benchmark comparing the two :-) jsbench.me/dfjtoadysr/1
– Falco
Mar 25 at 11:47
@MaheerAli Thank you - here is a benchmark comparing the two :-) jsbench.me/dfjtoadysr/1
– Falco
Mar 25 at 11:47
add a comment |
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Shouldn't the result be an object?
– Jack Bashford
Mar 25 at 7:02
@JackBashford Hey man, sry, u r right, I just updated it.
– SPG
Mar 25 at 7:08
Do you really want
includes
? I'd recommendstartsWith
– Bergi
Mar 25 at 8:26
@Bergi thx, I think
startWith
is better– SPG
Mar 26 at 0:30