I have an array with this values:
0:
code: "fb"
description: "Not relevant text."
did: 1
name: "Some random name"
sortOrder: 1
1:
code: "fr"
description: "Not relevant text."
did: 2
name: "Some random name"
sortOrder: 2
When i map the array like this:
values: this.stackOverflowExample.map(v => v.code).push(null)
And push a null code to the set, it sets all values to null
The output I want:
values: [
0: 'fb'
1: 'fr'
2: null ]
The output I got:
values: 3
How do I add values to the array this.stackOverflowExample
which is mapped by code, without affecting the other values?
The push method returns the new length of the array and not the mutated array, see documentation.
If you just want to append null to the mapped array you could either:
Concat your mapped array with [null]
values: anArray.map(mapFn).concat([null])
Spread your mapped array in an array with the last item being null
values: [...anArray.map(mapFn), null]
Related
I am working with dynamoose and a query returns me the following output
[ Document { cost: 100 },
lastKey: undefined,
count: 1,
queriedCount: undefined,
timesQueried: 1 ]
When I try to do typeof(output) , it returns Object
When I try to do Object.keys(output) , it returns [ '0', 'lastKey', 'count', 'queriedCount', 'timesQueried' ]
When I do Object.entries(output), it returns [ [ '0', Document { cost: 100 } ],[ 'lastKey', undefined ], [ 'count', 1 ], [ 'queriedCount', undefined ], [ 'timesQueried', 1 ] ]
For my use, I need to get an Object which looks like this {cost: 100} and currently I am using
JSON.parse(JSON.stringify(output))
which gives me
[ { cost: 100 } ]
I havent encountered an object without a key value pair (I'm self taught), so I do not know how to approach this problem. And the current method seems inefficient and kinda wrong. Please advice me how I can do it in a proper way
JSON.stringify(output) //=> "[ { cost: 100 } ]"
What that means is that you have an array (denoted by []) with one item, which is an object (denoted by {}) with a single key cost.
Use [0] to get the first item in an array, and then use .cost to get the cost property.
console.log(output[0].cost) //=> 100
The reason that you are seeing other keys on that array is that it looks like that dynamoose library is adding some additional properties to the array before returning it. It's doing the equivalent of:
// vanilla js, not typescript
const output = [ { cost: 100 } ]
output.count = 1
output.timesQueried = 1
This gives the array properties in addition to the content. The dynamoose library appears to use this method to encode metadata about your queries alongside the returned data.
The default JSON serialization strategy for arrays does not serialize custom array properties, only the array members.
I am trying to filter out an Object of Arrays wherein I have to filter out the 'designation' 'options' of a key.
My row Object looks like.
{id: 1, columns: Array(5)}
columns: (5) [InputDate, InputSelect, InputSelect, InputSelect, InputString]
id: 1
__proto__: Object
One of the columns Array where data is looks like this.
InputSelect
name: "designation"
options: Array(3)
0: {name: "Entry", value: "ENTRY"}
1: {name: "Mid", value: "MID"}
2: {name: "Experienced", value: "EXPERIENCE"}
length: 3
__proto__: Array(0)
Now I have to search inside the columns Arrays and filter out the options of "ENTRY" if the Arrays name property is 'designation' so as to return the updated Object having this filtered value.
What I am trying now is
row.columns.map( key => {
if (key.name === 'designation') {
key.options.filter( r => r.value === "ENTRY" )
}
But it doesn't seem to be updating the row Object.
This should solve your problem.
row.columns.filter(x=>x.name=="designation").map(i=>i.options.filter(z=>z.name==="Entry"));
I have a two sets of data, one formatted like so:
title: "Test Json",
showProgressBar: "top",
showQuestionNumbers: "off",
pages: [
{
questions: [
{
type: "",
name: "",
title: "",
hasOther: true,
isRequired: true,
colCount: 4,
choices: []
}
]
}
]
};
The other formatted like so:
{Answers: "“18-24”, “25-50”, “50+”",
Question: "How old are you?",
QuestionNumber: "1",
isRequired: "TRUE",
type: "radiogroup"}
This second set of data is multiple of these objects, which I am looping through using a forEach loop like so:
data.forEach((data, i)=>{
console.log(data)
// returns above object x3
})
What I want to do is use the first object and map values to the questions array using the values of the second object, so for example questions[0].type would be mapped to data.type.
I have managed to figure out mapping one object to the template doing this:
data.forEach((data, i)=>{
console.log(data)
questions[0].type = data.type
questions[0].name = data.Question
questions[0].title = data.Question
questions[0].choices = [data.Answers]
})
But this only maps the first object in the data array of objects, and I want to basically create a new template object based on the number of objects in the data array and create as many 'filled questions templates' as there is objects in data array
Any pointers and help would be lovely <3
Try this
data.forEach((data, i)=>{
console.log(data)
questions.push([{
type: data.type
name: data.Question
title: data.Question
choices: [data.Answers]
}])
})
Updated this answer with your additional question
So I am trying to combine 2 different javascript object than I can end up using in an angularjs ng-repeat . since there is a 1 to many relationship from the database, I was pulling queries separately.
What I have is this:
Main list of data , 3 object sample
0: Object
$$hashKey: "object:4"
Active:true
QuestionId:2
SalesChannel:"DTD"
1: Object
$$hashKey: "object:5"
Active:true
QuestionId:3
SalesChannel:"DTD"
2: Object
$$hashKey: "object:6"
Active:true
QuestionId:5
SalesChannel:"DTD"
Then another query returned data into what I want to relate as JSON into the other object
Object { Id: 3, Name: "Text box" QuestionId: 3}
{ Id: 4, Name: "Text box" QuestionId: 3}
{ Id: 9, Name: "Text box" QuestionId: 5}
So since I have both of these objects , I am wanting to combine.
Naturally I would think that I should return from the database, but then I also think about looping over and appending
for loop on main
{
.... find where main.QuestionId = sub.QuestionId and it to be added in as a nested object of json type...
Thus the end result SHOULD look like
[{
Active:true,
QuestionId: 3
SubData: [ {
Id: 3,
Name: "TextBox
QuestionId:3
},
{
Id: 4,
Name: "TextBox
QuestionId:3
}],
SalesChannel: "DTD"
}]
// and so on
How can i achieve this?
You want to go through all of the main objects, and assign to them only those results from second query. Use Array.prototype.forEach to go through them all, and Array.prototype.filter to select only appropriate results from secondary query.
firstQueryResult.forEach((firstObject)=>
firstObject.subdata = secondQueryResult.filter((secondObject)=>
secondObject.QuestionId === firstObject.QuestionId))
BTW, this has nothing to do with angularjs
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach
This question already has answers here:
How can I access and process nested objects, arrays, or JSON?
(31 answers)
Closed 6 years ago.
I'm attempting to use Javascript objects to work with some data. Here is the object itself (parsed from JSON) which is defined as accounts:
{
startIndex: 0,
pageSize: 20,
pageCount: 1,
totalCount: 1,
items: [
{
id: 123456,
emailAddress: 'test#test.com',
userName: 'test#test.com',
firstName: 'John',
lastName: 'Hancock',
customerSet: 'default',
commerceSummary: [
Object
],
contacts: [
Object
],
userId: '92834439c29389fj292',
notes: [
],
attributes: [
Object
],
segments: [
Object
],
taxExempt: false,
externalId: '2100010368',
isAnonymous: false,
auditInfo: [
Object
],
isLocked: false,
isActive: true,
hasExternalPassword: false,
customerSinceDate: 2016-06-23T18: 26: 46.000Z
}
]
}
While I can retrieve accounts.items without issue, I'm having some trouble retrieving individual values such as id or emailAddress from the item itself. Doing accounts.items[id] or accounts.items[emailAddress] does not work but I believe it's due to the fact that items can be more than 1 so I should be specifying the "first result" for items from that list. If that is the case, how do I retrieve the emailAddress or id for the first items array? The desired result from the above JSON object should be "123456" if id and "test#test.com" if email. Thanks in advance.
Your items is an array. You have to fetch data from it by indexes (like items[0]). If you are looking for an item, with their properties, use Array.find method.
The find method executes the callback function once for each element
present in the array until it finds one where callback returns a true
value. If such an element is found, find immediately returns the value
of that element. Otherwise, find returns undefined. callback is
invoked only for indexes of the array which have assigned values; it
is not invoked for indexes which have been deleted or which have never
been assigned values.
var accounts = {
startIndex: 0,
pageSize: 20,
pageCount: 1,
totalCount: 1,
items: [
{
id: 123456,
emailAddress: 'test#test.com',
userName: 'test#test.com',
firstName: 'John',
lastName: 'Hancock',
customerSet: 'default'
}
]
};
var sampleAccount = accounts.items.find(function (item) {
return item.id == 123456;
});
if (sampleAccount) {
console.log(sampleAccount.emailAddress);
}
You are right, first you need to reference the first element of the array. Then you can query its properties.
For example, to get the ID and email address of the first item you would write
accounts.items[0].id
accounts.items[0].emailAddress
Arrays elements start at index 0 in JavaScript, so the first element of the array has index 0, the second 1, and so on.
Items is an array and emailAddress is a Key, then you can get the value using:
accounts.items[0].emailAddress