How to insert objects through javascript? - javascript

I have stored group of objects into one array called 'resData' and i'm having one more array of data called 'approvedIds', there have included all approved id's. Here i want to match these two arrays and add one new key into 'resData' array like 'approveStatus:"approve"'. How to do this one in javascript?
All data's,
var resData = [
{
firstName:"Jhon",
lastName:"adam",
emailId:"jhn12#gmail.com",
id:"01"
},
{
firstName:"Kyle",
lastName:"Miller",
emailId:"kl12#gmail.com",
id:"02"
},
{
firstName:"Jhonathan",
lastName:"adam",
emailId:"jadm12#gmail.com",
id:"03"
},
{
firstName:"Lewis",
lastName:"harber",
emailId:"lewh12#gmail.com",
id:"04"
}
];
Approved id's array,
var approvedIds = ['01', '03'];
My output will be like this,
var resData = [
{
firstName:"Jhon",
lastName:"adam",
emailId:"jhn12#gmail.com",
id:"01",
approveStatus:'approved'
},
{
firstName:"Kyle",
lastName:"Miller",
emailId:"kl12#gmail.com",
id:"02"
},
{
firstName:"Jhonathan",
lastName:"adam",
emailId:"jadm12#gmail.com",
id:"03",
approveStatus:'approved'
},
{
firstName:"Lewis",
lastName:"harber",
emailId:"lewh12#gmail.com",
id:"04"
}
];


You can try this. Use forEach and indexOf functions
var resData = [
{
firstName:"Jhon",
lastName:"adam",
emailId:"jhn12#gmail.com",
id:"01"
},
{
firstName:"Kyle",
lastName:"Miller",
emailId:"kl12#gmail.com",
id:"02"
},
{
firstName:"Jhonathan",
lastName:"adam",
emailId:"jadm12#gmail.com",
id:"03"
},
{
firstName:"Lewis",
lastName:"harber",
emailId:"lewh12#gmail.com",
id:"04"
}
];
var approvedIds = ['01', '03'];
resData.forEach(item => {
if(approvedIds.indexOf(item.id) !== -1){
item.approvedStatus = 'approved';
}
} );
console.log(resData);


Using ES6 array functions, which is more functional and doesn't alter the original objects:
var resData = [
{
firstName:"Jhon",
lastName:"adam",
emailId:"jhn12#gmail.com",
id:"01"
},
{
firstName:"Kyle",
lastName:"Miller",
emailId:"kl12#gmail.com",
id:"02"
},
{
firstName:"Jhonathan",
lastName:"adam",
emailId:"jadm12#gmail.com",
id:"03"
},
{
firstName:"Lewis",
lastName:"harber",
emailId:"lewh12#gmail.com",
id:"04"
}
];
var approvedIds = ['01', '03'];
//Solution:
var newData = resData
.filter(rd => approvedIds.indexOf(rd.id) >= 0)
.map(rd => Object.assign({}, rd, {approvedStatus: "approved"}));
console.log(newData, resData);

Related

How to filter array and create new array with specific object keys

I have an array with objects and in each object there is an "items" array. My goal is to combine these "items" into one array.
Goal / Expected Output
[
{ id: 'SUV' },
{ id: 'Compact' },
{ id: 'Gasoline' },
{ id: 'Hybrid' }
]
Sample Array
[
{
"id":"carType",
"items":[
{
"id":"SUV"
},
{
"id":"Compact"
}
]
},
{
"id":"fuelType",
"items":[
{
"id":"Gasoline"
},
{
"id":"Hybrid"
}
]
}
]

You could use Array#flatMap.
const data = [{"id":"carType","items":[{"id":"SUV"},{"id":"Compact"}]},{"id":"fuelType","items":[{"id":"Gasoline"},{"id":"Hybrid"}]}];
const r = data.flatMap(({ items }) => items);
console.log(r);

A one-liner in vanilla JS (earlier than EMCAScript 2019, flatMap is not available, so in case of that...)
[].concat(...arr.map(elt => elt.items))

Something like this?
newArr = []
for (let i = 0;i<arr.length;i++) {
for (let ii = 0;ii<arr[i].items.length;ii++) {
newArr.push(arr[i].items[ii].id)
}
}
console.log(newArr)

Find Duplicate Array By Caption without using multiple loops [duplicate]

I need some help with iterating through array, I keep getting stuck or reinventing the wheel.
values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName1' },
{ name: 'someName1' }
]
How could I check if there are two (or more) same name value in array? I do not need a counter, just setting some variable if array values are not unique. Have in mind that array length is dynamic, also array values.

Use array.prototype.map and array.prototype.some:
var values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName2' }
];
var valueArr = values.map(function(item){ return item.name });
var isDuplicate = valueArr.some(function(item, idx){
return valueArr.indexOf(item) != idx
});
console.log(isDuplicate);

ECMA Script 6 Version
If you are in an environment which supports ECMA Script 6's Set, then you can use Array.prototype.some and a Set object, like this
let seen = new Set();
var hasDuplicates = values.some(function(currentObject) {
return seen.size === seen.add(currentObject.name).size;
});
Here, we insert each and every object's name into the Set and we check if the size before and after adding are the same. This works because Set.size returns a number based on unique data (set only adds entries if the data is unique). If/when you have duplicate names, the size won't increase (because the data won't be unique) which means that we would have already seen the current name and it will return true.
ECMA Script 5 Version
If you don't have Set support, then you can use a normal JavaScript object itself, like this
var seen = {};
var hasDuplicates = values.some(function(currentObject) {
if (seen.hasOwnProperty(currentObject.name)) {
// Current name is already seen
return true;
}
// Current name is being seen for the first time
return (seen[currentObject.name] = false);
});
The same can be written succinctly, like this
var seen = {};
var hasDuplicates = values.some(function (currentObject) {
return seen.hasOwnProperty(currentObject.name)
|| (seen[currentObject.name] = false);
});
Note: In both the cases, we use Array.prototype.some because it will short-circuit. The moment it gets a truthy value from the function, it will return true immediately, it will not process rest of the elements.

In TS and ES6 you can create a new Set with the property to be unique and compare it's size to the original array.
const values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName3' },
{ name: 'someName1' }
]
const uniqueValues = new Set(values.map(v => v.name));
if (uniqueValues.size < values.length) {
console.log('duplicates found')
}

To know if simple array has duplicates we can compare first and last indexes of the same value:
The function:
var hasDupsSimple = function(array) {
return array.some(function(value) { // .some will break as soon as duplicate found (no need to itterate over all array)
return array.indexOf(value) !== array.lastIndexOf(value); // comparing first and last indexes of the same value
})
}
Tests:
hasDupsSimple([1,2,3,4,2,7])
// => true
hasDupsSimple([1,2,3,4,8,7])
// => false
hasDupsSimple([1,"hello",3,"bye","hello",7])
// => true
For an array of objects we need to convert the objects values to a simple array first:
Converting array of objects to the simple array with map:
var hasDupsObjects = function(array) {
return array.map(function(value) {
return value.suit + value.rank
}).some(function(value, index, array) {
return array.indexOf(value) !== array.lastIndexOf(value);
})
}
Tests:
var cardHand = [
{ "suit":"spades", "rank":"ten" },
{ "suit":"diamonds", "rank":"ace" },
{ "suit":"hearts", "rank":"ten" },
{ "suit":"clubs", "rank":"two" },
{ "suit":"spades", "rank":"three" },
]
hasDupsObjects(cardHand);
// => false
var cardHand2 = [
{ "suit":"spades", "rank":"ten" },
{ "suit":"diamonds", "rank":"ace" },
{ "suit":"hearts", "rank":"ten" },
{ "suit":"clubs", "rank":"two" },
{ "suit":"spades", "rank":"ten" },
]
hasDupsObjects(cardHand2);
// => true

if you are looking for a boolean, the quickest way would be
var values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName1' },
{ name: 'someName1' }
]
// solution
var hasDuplicate = false;
values.map(v => v.name).sort().sort((a, b) => {
if (a === b) hasDuplicate = true
})
console.log('hasDuplicate', hasDuplicate)

const values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName4' }
];
const foundDuplicateName = values.find((nnn, index) =>{
return values.find((x, ind)=> x.name === nnn.name && index !== ind )
})
console.log(foundDuplicateName)
Found the first one duplicate name
const values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName4' }
];
const foundDuplicateName = values.find((nnn, index) =>{
return values.find((x, ind)=> x.name === nnn.name && index !== ind )
})

You just need one line of code.
var values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName2' }
];
let hasDuplicates = values.map(v => v.name).length > new Set(values.map(v => v.name)).size ? true : false;

Try an simple loop:
var repeat = [], tmp, i = 0;
while(i < values.length){
repeat.indexOf(tmp = values[i++].name) > -1 ? values.pop(i--) : repeat.push(tmp)
}
Demo

With Underscore.js A few ways with Underscore can be done. Here is one of them. Checking if the array is already unique.
function isNameUnique(values){
return _.uniq(values, function(v){ return v.name }).length == values.length
}
With vanilla JavaScript
By checking if there is no recurring names in the array.
function isNameUnique(values){
var names = values.map(function(v){ return v.name });
return !names.some(function(v){
return names.filter(function(w){ return w==v }).length>1
});
}

//checking duplicate elements in an array
var arr=[1,3,4,6,8,9,1,3,4,7];
var hp=new Map();
console.log(arr.sort());
var freq=0;
for(var i=1;i<arr.length;i++){
// console.log(arr[i-1]+" "+arr[i]);
if(arr[i]==arr[i-1]){
freq++;
}
else{
hp.set(arr[i-1],freq+1);
freq=0;
}
}
console.log(hp);

You can use map to return just the name, and then use this forEach trick to check if it exists at least twice:
var areAnyDuplicates = false;
values.map(function(obj) {
return obj.name;
}).forEach(function (element, index, arr) {
if (arr.indexOf(element) !== index) {
areAnyDuplicates = true;
}
});
Fiddle

Adding updated es6 function to check for unique and duplicate values in array. This function is modular and can be reused throughout the code base. Thanks to all the post above.
/* checks for unique keynames in array */
const checkForUnique = (arrToCheck, keyName) => {
/* make set to remove duplicates and compare to */
const uniqueValues = [...new Set(arrToCheck.map(v => v[keyName]))];
if(arrToCheck.length !== uniqueValues.length){
console.log('NOT UNIQUE')
return false
}
return true
}
let arr = [{name:'joshua'},{name:'tony'},{name:'joshua'}]
/* call function with arr and key to check for */
let isUnique = checkForUnique(arr,'name')

checkDuplicate(arr, item) {
const uniqueValues = new Set(arr.map((v) => v[item]));
return uniqueValues.size < arr.length;
},
console.log(this.checkDuplicate(this.dutyExemptionBase, 'CI_ExemptionType')); // true || false

It is quite interesting to work with arrays
You can use new Set() method to find duplicate values!
let's assume you have an array of objects like this...
let myArray = [
{ id: 0, name: "Jhon" },
{ id: 1, name: "sara" },
{ id: 2, name: "pop" },
{ id: 3, name: "sara" }
]
const findUnique = new Set(myArray.map(x => {
return x.name
}))
if(findUnique.size < myArray.length){
console.log("duplicates found!")
}else{
console.log("Done!")
}

const duplicateValues = [{ name: "abc" }, { name: "bcv" }, { name: "abc" }];
const isContainDuplicate = (params) => {
const removedDuplicate = new Set(params.map((el) => el.name));
return params.length !== removedDuplicate.size;
};
const isDuplicate = isContainDuplicate(duplicateValues);
console.log("isDuplicate");

Array of objects, combine values where key matches. with Underscore

Given the following array:
[
{
"real":104.1530776708426,
"workHour":8,
"value":null
},
{
"real":71.53948769310401,
"workHour":9
},
{
"real":97.84076993321577,
"workHour":10
},
{
"real":115.72564185649178,
"workHour":11
},
{
"real":79.95589800993977,
"workHour":12
},
{
"real":91.52846219558896,
"workHour":13
},
{
"real":57.86282092824589,
"workHour":14
},
{
"real":148.33923183423036,
"workHour":15
},
{
"real":125.19410346293202,
"workHour":16
},
{
"real":67.33128253468612,
"workHour":17
},
{
"real":55.75871834903695,
"workHour":18
},
{
"real":102.04897509163365,
"workHour":19
},
{
"real":132.55846249016332,
"workHour":20
},
{
"real":138.87077022779013,
"workHour":21
},
{
"real":60,
"workHour":8
},
{
"real":52,
"workHour":9
},
{
"real":114,
"workHour":10
},
{
"real":115,
"workHour":11
},
{
"real":92,
"workHour":12
},
{
"real":102,
"workHour":13
},
{
"real":54,
"workHour":14
},
{
"real":62,
"workHour":15
},
{
"real":133,
"workHour":16
},
{
"real":116,
"workHour":17
},
{
"real":106,
"workHour":18
},
{
"real":115,
"workHour":19
},
{
"real":115,
"workHour":20
},
{
"real":125,
"workHour":21
}
]
How can I find where the workHour match, and combine real there?
I did it with pure JS
const array = [{"real":104.1530776708426,"workHour":8,"value":null},{"real":71.53948769310401,"workHour":9},{"real":97.84076993321577,"workHour":10},{"real":115.72564185649178,"workHour":11},{"real":79.95589800993977,"workHour":12},{"real":91.52846219558896,"workHour":13},{"real":57.86282092824589,"workHour":14},{"real":148.33923183423036,"workHour":15},{"real":125.19410346293202,"workHour":16},{"real":67.33128253468612,"workHour":17},{"real":55.75871834903695,"workHour":18},{"real":102.04897509163365,"workHour":19},{"real":132.55846249016332,"workHour":20},{"real":138.87077022779013,"workHour":21},{"real":60,"workHour":8},{"real":52,"workHour":9},{"real":114,"workHour":10},{"real":115,"workHour":11},{"real":92,"workHour":12},{"real":102,"workHour":13},{"real":54,"workHour":14},{"real":62,"workHour":15},{"real":133,"workHour":16},{"real":116,"workHour":17},{"real":106,"workHour":18},{"real":115,"workHour":19},{"real":115,"workHour":20},{"real":125,"workHour":21}];
var map = {};
for (var i=0; i<array.length; i++) {
var obj = array[i],
id = obj.workHour;
if (id in map) { // we know this id already
// get the object and sum properties
map[id].real += obj.real;
} else // create a new one
map[id] = {
workHour: id,
real: obj.real,
};
}
console.log(map)
How can I do it with ES6? or Underscore?

Loop the array with Array#reduce to create a new object with combined values:
var data = [{"real":104.1530776708426,"workHour":8,"value":null},{"real":71.53948769310401,"workHour":9},{"real":97.84076993321577,"workHour":10},{"real":115.72564185649178,"workHour":11},{"real":79.95589800993977,"workHour":12},{"real":91.52846219558896,"workHour":13},{"real":57.86282092824589,"workHour":14},{"real":148.33923183423036,"workHour":15},{"real":125.19410346293202,"workHour":16},{"real":67.33128253468612,"workHour":17},{"real":55.75871834903695,"workHour":18},{"real":102.04897509163365,"workHour":19},{"real":132.55846249016332,"workHour":20},{"real":138.87077022779013,"workHour":21},{"real":60,"workHour":8},{"real":52,"workHour":9},{"real":114,"workHour":10},{"real":115,"workHour":11},{"real":92,"workHour":12},{"real":102,"workHour":13},{"real":54,"workHour":14},{"real":62,"workHour":15},{"real":133,"workHour":16},{"real":116,"workHour":17},{"real":106,"workHour":18},{"real":115,"workHour":19},{"real":115,"workHour":20},{"real":125,"workHour":21}];
var result = data.reduce(function(r, o) {
if (r[o.workHour]) {
r[o.workHour].real += o.real
} else {
r[o.workHour] = {
workHour: o.workHour,
real: o.real
}
}
return r;
}, {});
console.log(result);

Using lodash(/underscore), this uses _.reduce() with _.clone() to build an aggregate object. The values of this object are then output as an array of objects similar to your input array using _.values().
var data = [{"real":104.1530776708426,"workHour":8,"value":null},{"real":71.53948769310401,"workHour":9},{"real":97.84076993321577,"workHour":10},{"real":115.72564185649178,"workHour":11},{"real":79.95589800993977,"workHour":12},{"real":91.52846219558896,"workHour":13},{"real":57.86282092824589,"workHour":14},{"real":148.33923183423036,"workHour":15},{"real":125.19410346293202,"workHour":16},{"real":67.33128253468612,"workHour":17},{"real":55.75871834903695,"workHour":18},{"real":102.04897509163365,"workHour":19},{"real":132.55846249016332,"workHour":20},{"real":138.87077022779013,"workHour":21},{"real":60,"workHour":8},{"real":52,"workHour":9},{"real":114,"workHour":10},{"real":115,"workHour":11},{"real":92,"workHour":12},{"real":102,"workHour":13},{"real":54,"workHour":14},{"real":62,"workHour":15},{"real":133,"workHour":16},{"real":116,"workHour":17},{"real":106,"workHour":18},{"real":115,"workHour":19},{"real":115,"workHour":20},{"real":125,"workHour":21}];
var result = _.values(_.reduce(data, (sumObj, curr) => {
if (sumObj[curr.workHour])
sumObj[curr.workHour].real += curr.real;
else
sumObj[curr.workHour] = _.clone(curr);
return sumObj;
}, {}));
console.log(result);
.as-console-wrapper{top:0;max-height:100%!important;}
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

Removing duplicate values from two arrays

existing ["562fae5a626ca2e032947baa"]
new array [ { _id: '562fae5a626ca2e032947baa' },
{ _id: '562fae57626ca2e032947ba9' } ]
modified [ { _id: '562fae5a626ca2e032947baa' },
{ _id: '562fae57626ca2e032947ba9' } ]
I have an existing array and a new array, i want to compare the existing and the new array and remove the duplicates.
var existing = ["562fae5a626ca2e032947baa"];
var newArr = [ { _id: '562fae5a626ca2e032947baa' },
{ _id: '562fae57626ca2e032947ba9' } ];
newArr = newArr.filter(function(val){
return existing.indexOf(val) == -1;
});
console.log(newArr);
When i try to print newArr, i still get the two objects?
modified [ { _id: '562fae5a626ca2e032947baa' },
{ _id: '562fae57626ca2e032947ba9' } ]
I want the modified array to have only.
modified [{ _id: '562fae57626ca2e032947ba9' } ]
Below is the fiddle.
http://jsfiddle.net/ema6upg1/2/

newArr.filter(function(val){
return existing.indexOf(val._id) == -1;
})
is what you need, val is an object, you need to compare its _id

Your problem is, that one array contains objects.
var existing = ["562fae5a626ca2e032947baa"];
var newArr = [ { _id: '562fae5a626ca2e032947baa' },
{ _id: '562fae57626ca2e032947ba9' } ];
newArr = newArr.filter(function(val){
if(typeof val == "object") {
return existing.indexOf(val._id) == -1;
}
return existing.indexOf(val) == -1;
});
console.log(newArr);

The lookup for an object property is more efficient than iterating an array to find an id. Consider:
var existing = {
"562fae5a626ca2e032947baa": true
};
var newArr = [ { _id: '562fae5a626ca2e032947baa' },
{ _id: '562fae57626ca2e032947ba9' } ];
newArr.filter(function(val) {
return existing[val._id] || false;
}

How can I check if the array of objects have duplicate property values?

I need some help with iterating through array, I keep getting stuck or reinventing the wheel.
values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName1' },
{ name: 'someName1' }
]
How could I check if there are two (or more) same name value in array? I do not need a counter, just setting some variable if array values are not unique. Have in mind that array length is dynamic, also array values.

Use array.prototype.map and array.prototype.some:
var values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName2' }
];
var valueArr = values.map(function(item){ return item.name });
var isDuplicate = valueArr.some(function(item, idx){
return valueArr.indexOf(item) != idx
});
console.log(isDuplicate);

ECMA Script 6 Version
If you are in an environment which supports ECMA Script 6's Set, then you can use Array.prototype.some and a Set object, like this
let seen = new Set();
var hasDuplicates = values.some(function(currentObject) {
return seen.size === seen.add(currentObject.name).size;
});
Here, we insert each and every object's name into the Set and we check if the size before and after adding are the same. This works because Set.size returns a number based on unique data (set only adds entries if the data is unique). If/when you have duplicate names, the size won't increase (because the data won't be unique) which means that we would have already seen the current name and it will return true.
ECMA Script 5 Version
If you don't have Set support, then you can use a normal JavaScript object itself, like this
var seen = {};
var hasDuplicates = values.some(function(currentObject) {
if (seen.hasOwnProperty(currentObject.name)) {
// Current name is already seen
return true;
}
// Current name is being seen for the first time
return (seen[currentObject.name] = false);
});
The same can be written succinctly, like this
var seen = {};
var hasDuplicates = values.some(function (currentObject) {
return seen.hasOwnProperty(currentObject.name)
|| (seen[currentObject.name] = false);
});
Note: In both the cases, we use Array.prototype.some because it will short-circuit. The moment it gets a truthy value from the function, it will return true immediately, it will not process rest of the elements.

In TS and ES6 you can create a new Set with the property to be unique and compare it's size to the original array.
const values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName3' },
{ name: 'someName1' }
]
const uniqueValues = new Set(values.map(v => v.name));
if (uniqueValues.size < values.length) {
console.log('duplicates found')
}

To know if simple array has duplicates we can compare first and last indexes of the same value:
The function:
var hasDupsSimple = function(array) {
return array.some(function(value) { // .some will break as soon as duplicate found (no need to itterate over all array)
return array.indexOf(value) !== array.lastIndexOf(value); // comparing first and last indexes of the same value
})
}
Tests:
hasDupsSimple([1,2,3,4,2,7])
// => true
hasDupsSimple([1,2,3,4,8,7])
// => false
hasDupsSimple([1,"hello",3,"bye","hello",7])
// => true
For an array of objects we need to convert the objects values to a simple array first:
Converting array of objects to the simple array with map:
var hasDupsObjects = function(array) {
return array.map(function(value) {
return value.suit + value.rank
}).some(function(value, index, array) {
return array.indexOf(value) !== array.lastIndexOf(value);
})
}
Tests:
var cardHand = [
{ "suit":"spades", "rank":"ten" },
{ "suit":"diamonds", "rank":"ace" },
{ "suit":"hearts", "rank":"ten" },
{ "suit":"clubs", "rank":"two" },
{ "suit":"spades", "rank":"three" },
]
hasDupsObjects(cardHand);
// => false
var cardHand2 = [
{ "suit":"spades", "rank":"ten" },
{ "suit":"diamonds", "rank":"ace" },
{ "suit":"hearts", "rank":"ten" },
{ "suit":"clubs", "rank":"two" },
{ "suit":"spades", "rank":"ten" },
]
hasDupsObjects(cardHand2);
// => true

if you are looking for a boolean, the quickest way would be
var values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName1' },
{ name: 'someName1' }
]
// solution
var hasDuplicate = false;
values.map(v => v.name).sort().sort((a, b) => {
if (a === b) hasDuplicate = true
})
console.log('hasDuplicate', hasDuplicate)

const values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName4' }
];
const foundDuplicateName = values.find((nnn, index) =>{
return values.find((x, ind)=> x.name === nnn.name && index !== ind )
})
console.log(foundDuplicateName)
Found the first one duplicate name
const values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName4' }
];
const foundDuplicateName = values.find((nnn, index) =>{
return values.find((x, ind)=> x.name === nnn.name && index !== ind )
})

You just need one line of code.
var values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName2' }
];
let hasDuplicates = values.map(v => v.name).length > new Set(values.map(v => v.name)).size ? true : false;

Try an simple loop:
var repeat = [], tmp, i = 0;
while(i < values.length){
repeat.indexOf(tmp = values[i++].name) > -1 ? values.pop(i--) : repeat.push(tmp)
}
Demo

With Underscore.js A few ways with Underscore can be done. Here is one of them. Checking if the array is already unique.
function isNameUnique(values){
return _.uniq(values, function(v){ return v.name }).length == values.length
}
With vanilla JavaScript
By checking if there is no recurring names in the array.
function isNameUnique(values){
var names = values.map(function(v){ return v.name });
return !names.some(function(v){
return names.filter(function(w){ return w==v }).length>1
});
}

//checking duplicate elements in an array
var arr=[1,3,4,6,8,9,1,3,4,7];
var hp=new Map();
console.log(arr.sort());
var freq=0;
for(var i=1;i<arr.length;i++){
// console.log(arr[i-1]+" "+arr[i]);
if(arr[i]==arr[i-1]){
freq++;
}
else{
hp.set(arr[i-1],freq+1);
freq=0;
}
}
console.log(hp);

You can use map to return just the name, and then use this forEach trick to check if it exists at least twice:
var areAnyDuplicates = false;
values.map(function(obj) {
return obj.name;
}).forEach(function (element, index, arr) {
if (arr.indexOf(element) !== index) {
areAnyDuplicates = true;
}
});
Fiddle

Adding updated es6 function to check for unique and duplicate values in array. This function is modular and can be reused throughout the code base. Thanks to all the post above.
/* checks for unique keynames in array */
const checkForUnique = (arrToCheck, keyName) => {
/* make set to remove duplicates and compare to */
const uniqueValues = [...new Set(arrToCheck.map(v => v[keyName]))];
if(arrToCheck.length !== uniqueValues.length){
console.log('NOT UNIQUE')
return false
}
return true
}
let arr = [{name:'joshua'},{name:'tony'},{name:'joshua'}]
/* call function with arr and key to check for */
let isUnique = checkForUnique(arr,'name')

checkDuplicate(arr, item) {
const uniqueValues = new Set(arr.map((v) => v[item]));
return uniqueValues.size < arr.length;
},
console.log(this.checkDuplicate(this.dutyExemptionBase, 'CI_ExemptionType')); // true || false

It is quite interesting to work with arrays
You can use new Set() method to find duplicate values!
let's assume you have an array of objects like this...
let myArray = [
{ id: 0, name: "Jhon" },
{ id: 1, name: "sara" },
{ id: 2, name: "pop" },
{ id: 3, name: "sara" }
]
const findUnique = new Set(myArray.map(x => {
return x.name
}))
if(findUnique.size < myArray.length){
console.log("duplicates found!")
}else{
console.log("Done!")
}

const duplicateValues = [{ name: "abc" }, { name: "bcv" }, { name: "abc" }];
const isContainDuplicate = (params) => {
const removedDuplicate = new Set(params.map((el) => el.name));
return params.length !== removedDuplicate.size;
};
const isDuplicate = isContainDuplicate(duplicateValues);
console.log("isDuplicate");

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