Check if a string is in a list or not (JavaScript)

Question

I have a list as below:

var myList = [{type:'Prospect__c', typeName__c:'high_school', },
{type:'Procedure__c', typeName__c:'in_program', },
{type:'Procedure__c', typeName__c:'attention_plz', }]

I want to check if in_program (which is present in my list), exists in my list or not? I've used different types of codes in order to get the result but I did not succeed.

Here are some of my tries:

if (myList.indexOf('in_program')>0)

if (myList.indexOf(typeName__c:'in_program')>0)

if (myList.indexOf(" typeName__c:'in_program' ")>0)

@reshad a useful reference: http://stackoverflow.com/questions/22844560/check-if-object-value-exists-within-a-javascript-array-of-objects-and-if-not-add — Rajesh, Nov 08 '16 at 14:10
@Hoyen if its just about finding existance of value, I'd suggest `array.some` — Rajesh, Nov 08 '16 at 14:10
@reshad Glad I could help! Also I have added an answer and have explained few methods based on cases. Hope it helps — Rajesh, Nov 08 '16 at 14:18

score 2 · Answer 1 · answered Nov 08 '16 at 14:12

There are a bunch of different strategies you can follow, but indexOf would only work if you were looking for the exact same root object, not one of its properties

A good approach would be with filter:

var filteredItems = myList.filter(function(a) { 
  return a.typeName__c === 'in_program' 
})
console.log(filteredItems.length === 0) // false

This will return a new collection with the items filtered by the returned value of the callback. Then, you check the length and see if it's 0 or greater.

score 2 · Answer 2 · answered Nov 08 '16 at 14:13

2

You can use Array.some:

var isInList = myList.some(function (obj) {
    return 'in_program' === obj.typeName__c;
});

answered Nov 08 '16 at 14:13

Hyddan

1,297
15
24

score 2 · Accepted Answer · edited Jun 20 '20 at 09:12

You can use following approach in different scenario:

JSON.stringify

If its just about finding availability, you can get JSON string and then check in it.

As correctly pointed by corn3lius, just checking search value will search in keys as well. You can wrap searchValue in ":..." and this will only search in values

var myList = [{type:'Prospect__c', typeName__c:'high_school', },
{type:'Procedure__c', typeName__c:'in_program', },
{type:'Procedure__c', typeName__c:'attention_plz', }]
var searchVal = 'in_program';

var exist= JSON.stringify(myList).indexOf(":\"" + searchVal + "\"") > -1;

console.log(exist)

Array.some

An alternate could be using array function if you know the exact key to lookup

var myList = [{type:'Prospect__c', typeName__c:'high_school', },
{type:'Procedure__c', typeName__c:'in_program', },
{type:'Procedure__c', typeName__c:'attention_plz', }]
var searchVal = 'in_program';

var exist= myList.some(function(o){ return o.typeName__c === searchVal });

console.log(exist)

Array.find

If you want to find first object where value matches, you should use Array.find

var myList = [{type:'Prospect__c', typeName__c:'high_school', },
{type:'Procedure__c', typeName__c:'in_program', },
{type:'Procedure__c', typeName__c:'attention_plz', }]
var searchVal = 'in_program';

var exist= myList.find(function(o){ return o.typeName__c === searchVal });

console.log(exist)

Array.filter

If you want to find all objects where value matches, you should use Array.filter

var myList = [{type:'Prospect__c', typeName__c:'high_school', },
{type:'Procedure__c', typeName__c:'in_program', },
{type:'Procedure__c', typeName__c:'attention_plz', }]
var searchVal = 'Procedure__c';

var exist= myList.filter(function(o){ return o.type === searchVal });

console.log(exist)

stringify solution doesn't account for the search result being in a key or the value of another key. — corn3lius, Nov 08 '16 at 14:18
@corn3lius Thanks for pointing it out. I have updated my answer and have credited you. — Rajesh, Nov 08 '16 at 14:22

score 1 · Answer 4 · answered Nov 08 '16 at 14:10

Check the code below:

var myList = [{type:'Prospect__c', typeName__c:'high_school', },
{type:'Procedure__c', typeName__c:'in_program', },
{type:'Procedure__c', typeName__c:'attention_plz', }];

var length = myList.length;

for(i = 0; i < length ; i++){

    if(myList[i].typeName__c == 'in_program')
  {
    alert("true");
  }
}

corn3lius · Answer 5 · 2016-11-08T14:13:42.120

1

var entry = mylist.find(function(e){ return e.typeName__c === 'in_program'; });
if( entry ) {
   // found object in list 
}

documented here : https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find

edited Nov 08 '16 at 14:13

answered Nov 08 '16 at 14:10

corn3lius

4,857
2
31
36

`mylist.find(e => e.typeName__c === 'in__program');` – craigmichaelmartin Nov 08 '16 at 14:12

Check if a string is in a list or not (JavaScript)

5 Answers5

JSON.stringify

Array.some

Array.find

Array.filter