Find an element in an array of objects

Question

Array looks so:

var arr = 
[{name: '1112B', 
 subname: 
 [
 {name: 'sub_1112B'}, 
 {name: 'sub_1112BA'}
 ]
 }, 
 {name: '2112B', 
 subname: 
 [
 {name: 'sub_2112B'},
 {name: 'sub_2112BA'}
 ]
 }];

After executing following code: arr.map(it => it.subname).find(i => i.name == 'sub_2112BA') i got undefined but it is supposed to be '2112B'.

What am I doing wrong?

• Mohammad Usman: Your test string sub2112BA doesn't exists in your data.
• ENG1959: sub_2112BA exists in name: '2112B'

Answer 1

arr.map(it => it.subname) will create nested array of subname and using .find() will return undefined since it iterate through a nested array, you could use .flat() and then use findafter but it won't return the object containing the subname since you are iterating in the subname array, so instead you can filter the objects of the array and use find on each subname array to check if the desired nameis there

arr = 
[{name: '1112B', 
 subname: 
 [
 {name: 'sub_1112B'}, 
 {name: 'sub_1112BA'}
 ]
 }, 
 {name: '2112B', 
 subname: 
 [
 {name: 'sub_2112B'},
 {name: 'sub_2112BA'}
 ]
 }];
 
 res=arr.filter(x=>(x.subname.find(y=>y.name=="sub_2112B")))
 console.log(res)

• balajisoundar: Array.prototype.filter returns an array and also it will loop through the entire array. if you're really interested in first occurrence, can go with x.find(d => !!d.subname.find(i => i.name == 'sub_2112BA'))
• Sven.hig: @ENG1959 Please conceder accepting my answer if it helped clarifying the problem

Answer 2

Use type-safe equal === in find()

• genius42: Also you will find not find the string your looking for, but rather the object containing the string. You should not include the map call, if you want to get the object containing the search as a substring.