I am new to javascript and I tried like using distinct but its not what im looking for
example array:
let arr = [ {key:"1",value:"dog"},
{key:"1",value:"dog"},
{key:"2",value:"cat"},
{key:"3",value:"bird"},
{key:"3",value:"bird"},
]
on the code I try is its just removing the duplicate like
[ {key:"1",value:"dog"},
{key:"2",value:"cat"},
{key:"3",value:"bird"}, ]
how can I get only the
[ {key:"2",value:"cat"} ]
what I mean is only the one who have no duplicate and its removing those array that have the exact same?
You can map your objects to stringified versions of your objects so you can then use .indexOf and .lastIndexOf() to compare if the object found appears in different locations in your array, if the last and first index appear in the same location then it can be said that they're the same object (ie: a duplicate doesn't exist) and can be kept in your resulting array like so:
const arr = [{key:"1",value:"dog"},{key:"1",value:"dog"},{key:"2",value:"cat"},{key:"3",value:"bird"},{key:"3",value:"bird"}];
const searchable = arr.map(JSON.stringify);
const res = arr.filter((obj, i) => {
const str = JSON.stringify(obj);
return searchable.indexOf(str) === searchable.lastIndexOf(str);
});
console.log(res);
If you can use Javascript libraries such as underscore or lodash, I recommend having a look at _.xorBy function in their libraries. From lodash:
_.xorBy([arrays], [iteratee=_.identity])
Basically, you pass in the array that in here is an object literal and you pass in the attribute that you want to all occurrences of remove duplicates with in the original data array, like this:
var data = [ {key:"1",value:"dog"}
, {key:"1",value:"dog"}
, {key:"2",value:"cat"}
, {key:"3",value:"bird"}
, {key:"3",value:"bird"}
];
var non_duplidated_data = _.xorBy(data, 'key');
Source - https://lodash.com/docs/4.17.14#xorBy
You can use reduce and Map
let arr = [{key:"1",value:"dog"},{key:"1",value:"dog"},{key:"2",value:"cat"},{key:"3",value:"bird"},{key:"3",value:"bird"}]
let mapper = arr.reduce( (op,inp) => {
let {key} = inp
op.set(key, op.get(key) || {value: inp, count:0})
op.get(key).count++
return op
},new Map())
let final = [...mapper.values()].reduce((op,{value,count}) => {
if(count === 1){
op.push(value)
}
return op
},[])
console.log(final)
Using the "find" method, you will get exactly what you are looking for "{key:"2",value:"cat"}".
arr.find((item, index) => {
const foundDup = arr.find((s, sIndex) => sIndex !== index && s.key === item.key);
return !foundDup;
});
If you don't mind using a library, I strongly suggest using the "ramda" library.
const arr = [ {key:"1",value:"dog"}
, {key:"1",value:"dog"}
, {key:"2",value:"cat"}
, {key:"3",value:"bird"}
, {key:"3",value:"bird"}
];
const result = R.uniq(arr);
result will be:
[{"key": "1", "value": "dog"}, {"key": "2", "value": "cat"}, {"key": "3", "value": "bird"}]
you can use "lodash" or other similar libraries too.
Related
I am trying to filter an object with another object inside of an array.
To be more precise, I am trying to compare the keys of the object inside the array, to the keys of my main object. If the values are the same, I want to return the value corresponding to those keys.
Here's an example:
var a = {
"maths":"A++",
"literature":"C-",
"sports":"B+",
"biology":"D",
"chemistry":"A",
"english":"A+",
"physics":"C+"
}
var b = [{
"maths":"Mathematics",
"biology":"Biology",
"physics":"Physics"
}]
I wanna check if any of the keys in object b are inside object a and if they are, I want to return their value into array. For example, I want to return ["A++","D","C+"]
I've tried using filter and Array.prototype.some but I couldn't figure out anything. Any advice on how should I achieve this?
First make an array or Set of all the keys inside b, then use .map to access each key on the a object:
var a = {
"maths":"A++",
"literature":"C-",
"sports":"B+",
"biology":"D",
"chemistry":"A",
"english":"A+",
"physics":"C+"
}
var b = [{
"maths":"Mathematics",
"biology":"Biology",
"physics":"Physics"
}];
const keys = b.flatMap(Object.keys);
const arr = keys.map(key => a[key]);
console.log(arr);
I'm assuming that you want to handle multiple objects in b.
If so and if you want one array for each object in b then you could do something like:
var a = {
"maths":"A++",
"literature":"C-",
"sports":"B+",
"biology":"D",
"chemistry":"A",
"english":"A+",
"physics":"C+"
}
var b = [{
"maths":"Mathematics",
"biology":"Biology",
"physics":"Physics"
},{
"maths":"Mathematics",
"biology":"Biology",
"english":"English"
}]
const result = b.map(obj => Object.keys(obj).map(key => a[key]));
console.log(result);
If you are dealing with a single object in the array b, then you can do this:
var a = {
"maths":"A++",
"literature":"C-",
"sports":"B+",
"biology":"D",
"chemistry":"A",
"english":"A+",
"physics":"C+"
}
var b = [{
"maths":"Mathematics",
"biology":"Biology",
"physics":"Physics"
}]
const valuesInAndB = Object.keys(a).reduce((acc,x) => {
if (b[0][x]) {
return acc.concat(a[x]);
}
return acc;
}, []);
console.log(valuesInAndB);
However, if the objects in b will be greater than one then as answered by #certainperformance you could get all the keys in b and map through a with those keys.
const keysInB = b.flatMap(Object.keys);
keysInB.map(key => a[key]);
flatMap is not available in some older browsers, please keep that in mind.
I want to merge two arrays both array contains another array inside. refer below two arrays.
const arr1=
[{"projectId":30278,"projectName":null,"details":[{"amount":"9097457.11","currency":"USD","paymentDate":"2016-05-16T00:00:00"}]},{"projectId":37602,"projectName":null,"details":[{"amount":"8234743.0","currency":"USD","paymentDate":"2019-04-30T00:00:00"},{"amount":"8234743.0","currency":"USD","paymentDate":"2019-04-23T00:00:00"}]}]
const arr2=
[{"projectId":30278,"projectName":null,"details":[{"amount":"8097457.11","currency":"USD","paymentDate":"2016-05-16T00:00:00"}]},{"projectId":37602,"projectName":null,"details":[{"amount":"7234743.0","currency":"USD","paymentDate":"2019-04-30T00:00:00"},{"amount":"7234743.0","currency":"USD","paymentDate":"2019-04-23T00:00:00"}]}]
when i used ES6 spread operator, both values are appended to single array. But I want to merge based upon prjectId in that array.
So after merge, i need to get the result like below
const result =
[{"projectId":30278,"projectName":null,"details":[{"amount":"9097457.11","currency":"USD","paymentDate":"2016-05-16T00:00:00"},
{"amount":"8097457.11","currency":"USD","paymentDate":"2016-05-16T00:00:00"}
]},
{"projectId":37602,"projectName":null,"details":[{"amount":"8234743.0","currency":"USD","paymentDate":"2019-04-30T00:00:00"},{"amount":"8234743.0","currency":"USD","paymentDate":"2019-04-23T00:00:00"},
{"amount":"7234743.0","currency":"USD","paymentDate":"2019-04-30T00:00:00"},{"amount":"7234743.0","currency":"USD","paymentDate":"2019-04-23T00:00:00"}
]}]
const arr1=
[{"projectId":30278,"projectName":null,"details":[{"amount":"9097457.11","currency":"USD","paymentDate":"2016-05-16T00:00:00"}]},{"projectId":37602,"projectName":null,"details":[{"amount":"8234743.0","currency":"USD","paymentDate":"2019-04-30T00:00:00"},{"amount":"8234743.0","currency":"USD","paymentDate":"2019-04-23T00:00:00"}]}]
const arr2=
[{"projectId":30278,"projectName":null,"details":[{"amount":"8097457.11","currency":"USD","paymentDate":"2016-05-16T00:00:00"}]},{"projectId":37602,"projectName":null,"details":[{"amount":"7234743.0","currency":"USD","paymentDate":"2019-04-30T00:00:00"},{"amount":"7234743.0","currency":"USD","paymentDate":"2019-04-23T00:00:00"}]}]
var fullArray = [...arr1,...arr2];
var mergedData ={};
fullArray.forEach(function(data){
if(mergedData[data.projectId]){
mergedData[data.projectId]["details"] = mergedData[data.projectId]["details"].concat(data.details)
} else {
mergedData[data.projectId] = data;
}
})
console.log(Object.values(mergedData))
You can easily achieve that using Lodash unionBy function.
const result = _.unionBy(arr1, arr2, 'projectId')
You can also try this in this case scenario.
let mergedArr = [];
let projectIdsArr1 = arr1.map(item => item.projectId);
arr2.map(outerLoopItem => {
if (projectIdsArr1.includes(outerLoopItem.projectId)) {
let found = arr1.find(innerLoopItem => innerLoopItem.projectId === outerLoopItem.projectId);
found.details = [...found.details, ...outerLoopItem.details];
mergedArr.push(found);
} else mergedArr.push(outerLoopItem);
});
console.log(mergedArr);
I have big array, which looks like this example:
let array = ['aa-we', 'aa-we__qq', 'aa-we__qw', 'gsPlsOdd', 'bc-po-lp', 'bc-po-lp--ps', 'de', 'de__io', 'de__sl', 'de--xz', 'ccsDdd'];
i want split this array into small arrays by values:
let array = [
['aa-we', 'aa-we__qq', 'aa-we__qw'],
['bc-po-lp', 'bc-po-lp--ps'],
['de', 'de__io', 'de__sl', 'de--xz']
]
// and camelcase strings should be removed
Values in array have syntax like BEM selectors, so if the prefix of different strings is the same, they should be wrapped in a single array.
How can i do this, if possible, without additional libraries?
Thanks for the help or tips!
console.clear()
let data = [
"aa-we",
"aa-we__qq",
"aa-we__qw",
"gsPlsOdd",
"bc-po-lp",
"bc-po-lp--ps",
"de",
"de__io",
"de__sl",
"de--xz",
"ccsDdd",
];
resultO = data.reduce((acc, val, idx) => {
if (val.match(/[A-Z]/)) {return acc;}
const sel = val.replace(/^(.*)(__|--).*$/g, "$1");
acc[sel] = acc[sel] || [];
acc[sel].push(val)
return acc;
}, {})
resultA = Object.values(resultO)
console.log(resultA)
I'd do something like this and then filter out what you don't want.
let array = ['aa-we', 'aa-we__qq', 'aa-we__qw', 'gsPlsOdd', 'bc-po-lp', 'bc-po-lp--ps', 'de', 'de__io', 'de__sl', 'de--xz', 'ccsDdd'];
array = array.filter((a) => !a.match(/[A-Z]/))
let result = groupBy(array, (str)=> str.split(/[-_]/)[0])
console.log(Object.values(result))
function groupBy(arr, condition) {
return arr.reduce((result, current) => {
const key = condition(current);
(result[key] || (result[key] = [])).push(current)
return result
}, {})
}
The algorithm can be as follows:
Create Map<Prefix,ValuesArray>
For each element in array:
Get it's prefix, e.g. "ab", skip element if invalid (e.g. no prefix exist or camel case)
Add to corresponding hashed bucket
Join values from Map into one array
JS has all the primitives to implement this, just take a look at Map/Object for hashing and Array (map/filter/reduce) for processing.
I have a array called data inside that array I have objects.
An object structure is like this
{
id:1,
especial_id:34,
restaurant_item:{id:1,restaurant:{res_name:'KFC'}}
}
I want to pass a res_name eg:- KFC
I want an output as a array which consists all the especial_ids
like this
myarr = [12,23,23]
I could do something like this for that. But I want to know what is more elegant way to do this.
const data = [
{id:1,especial_id:6,restaurant_items:{id:5,res_name:'McDonalds'}},
{id:1,especial_id:8,restaurant_items:{id:5,res_name:'Kfc'}},
{id:1,especial_id:6,restaurant_items:{id:5,res_name:'Sunmeal'}},
{id:1,especial_id:6,restaurant_items:{id:5,res_name:'Kfc'}},
];
let temp = data.filter(element => element.restaurant_items.res_name == 'kfc')
let myArr = [];
temp.forEach(element=> myArr.push(element.especial_id));
console.log(myArr)//[8,6]
You can try this. It uses "Array.filter" and "Array.map"
var data = [
{id:1,especial_id:6,restaurant_items:{id:5,res_name:'McDonalds'}},
{id:1,especial_id:8,restaurant_items:{id:5,res_name:'Kfc'}},
{id:1,especial_id:6,restaurant_items:{id:5,res_name:'Sunmeal'}},
{id:1,especial_id:6,restaurant_items:{id:5,res_name:'Kfc'}},
];
function getEspecialIdsByName(name) {
return data.filter(d => d.restaurant_items.res_name.toLowerCase() == name.toLowerCase())
.map(d => d.especial_id)
}
console.log(getEspecialIdsByName('Kfc'))
console.log(getEspecialIdsByName('Sunmeal'))
You can reduce to push elements which pass the test to the accumulator array in a single iteration over the input:
const data = [
{id:1,especial_id:6,restaurant_items:{id:5,res_name:'McDonalds'}},
{id:1,especial_id:8,restaurant_items:{id:5,res_name:'Kfc'}},
{id:1,especial_id:6,restaurant_items:{id:5,res_name:'Sunmeal'}},
{id:1,especial_id:6,restaurant_items:{id:5,res_name:'Kfc'}},
];
console.log(
data.reduce((a, { especial_id, restaurant_items: { res_name }}) => {
if (res_name === 'Kfc') a.push(especial_id)
return a;
}, [])
);
Use Array.reduce
const data = [{id:1,especial_id:6,restaurant_items:{id:5,res_name:'McDonalds'}},{id:1,especial_id:8,restaurant_items:{id:5,res_name:'Kfc'}},{id:1,especial_id:6,restaurant_items:{id:5,res_name:'Sunmeal'}},{id:1,especial_id:6,restaurant_items:{id:5,res_name:'Kfc'}}];
let result = data.reduce((a,c) => {
if(c.restaurant_items.res_name === 'Kfc') a.push(c.especial_id);
return a;
},[]);
console.log(result);
As a ReactJS newbie, I tried to parse RestfulAPI JSON reponse, But, I couldn't retrieve all elements. While trying to access text.subjects.code and text.subjects.description, it returns null. However, I could successfully access text.id and text.name.
JSON response is given below.
[
{
"id":95822,
"name":"Alex",
"subjects":[
{
"code": "101",
"description": "Course 101"
}
]
}
]
Kindly advise.
You can do iteration in many ways and few ways which I always prefer using .forEach and .map
If you need new array then go with .map. Because map returns a new array
const dataArray = text.subjects.map(subject => {
let obj = {};
obj.code = subject.code;
obj.description = subject.description;
return obj;
});
//dataArray will contain all the objects
There is also a Different way of doing map
const dataArray = text.subjects.map(subject => (
let obj = {};
obj.code = subject.code;
obj.description = subject.description;
return obj;
);
Or if you want to just iterate the data then use .forEach. forEach doesn’t return an array
let array = [];
text.subjects.forEach(subject => (
let obj = {};
obj.code = subject.code;
obj.description = subject.description;
array.push(obj);
));
if You check subjects is an array and you are not getting value from it, try
text.subjects[0].code
Because subjects is an array and you should map subject like the following:
text.subjects.map((subject) => {
console.log(subject.code, subject.description);
})
or directly get the index that you to want like the following:
text.subjects[0].code