+ 1

Access elements of a object inside a object

Suppose this is the object inside object: let MyObject = { person : [ { name: "abc", age: 100 }, { name: "xyz", age: 20 } ] } Suppose I want to get the 2nd person's name Though i can access like this console.log(MyObject.person[1].name); But what if i don't know the index of that element thats is [1] in this case ? (Imagine there are 100 of such objects inside the MyObject and I want to access a random one out of it) So how can i access it without knowing the index of the object in that array?

1st May 2021, 4:18 AM
PRATHIK
PRATHIK - avatar
6 Answers
+ 3
Let's say you want to find a person by name rather than by index, you could use a `for of` loop: const findPerson = (name, persons) => { for(person of persons){ if(person.name == name) return person } return false } let person = findPerson("xyz", MyObject.person) However, I personally make use of Array functions based on the many different use cases. The following is an equivalent to the previous code: let person = (MyObject.person .find(item => item.name == "xyz") ?? false) Things can get more advanced from here. But, this should give you an idea.
1st May 2021, 4:38 AM
David Carroll
David Carroll - avatar
+ 2
[Part 3 of 3 Follow Up] So... finally you can remove the isMatch function and replace the following: items.find(isMatch) with: items.find(item => item === "xyz") It's all equivalent. Hopefully, this gives you a clearer understanding. 😉👌
1st May 2021, 5:38 AM
David Carroll
David Carroll - avatar
+ 1
David Carroll Can u pls explain me a bit about the last 3rd and 4th line 😅(sry for inconvenience I understood it now ) Thanks for helping @David Carroll
1st May 2021, 4:43 AM
PRATHIK
PRATHIK - avatar
+ 1
[Part 1 of 3 Follow Up] Spend some time reading about this on the MDN website: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find I'll try to shorten the code to focus on the key parts: const items = [ {name: "abc"}, {name: "xyz"} ] items.find(item => item.name === "xyz") NOTE: `items` is an Array. Arrays have specific methods that allow for additional capabilities for iterating items. Many of these Array methods, like Array.find(...) expect a function that returns a Boolean value to indicate if an item is a match. These functions are known as predicates. The predicate function used for Array.find() requires an arg for the current item of an array. This predicate could have been written as: function isMatch(item) { return item.name === "xyz" } items.find(isMatch) Note: isMatch function is passed to the Array.find() method as a predicate function. (continued...)
1st May 2021, 5:22 AM
David Carroll
David Carroll - avatar
+ 1
[Part 2 of 3 Follow Up] Now... let's rewrite isMatch as an arrow function: const isMatch = (item) => { return item.name === "xyz" } This particular arrow function can be simplified by removing the (...), {...}, and the `return` keyword: const isMatch = item => item.name === "xyz" Again... the above line is equivalent to the earlier named function: function isMatch(item) { return item.name === "xyz" } Visually compare the two examples to build a mental map of each part of the different function types. Essentially... the left side of the arrow "=>" defines the parameter arg "(item)" and the right side defines the function body with an implicit return statement: { return item.name === "xyz" } A reference to `isMatch` - without the parenthesis - is the equivalent of defining an arrow function and passing it without a name: item => item.name === "xyz" This is known as an anonymous function, where isMatch is a named function.
1st May 2021, 5:29 AM
David Carroll
David Carroll - avatar
+ 1
David Carroll Yes , this has given me a very good idea about not only my question but i also learnt a bit of few new things in js .Thanks a lot for ur help.
1st May 2021, 5:42 AM
PRATHIK
PRATHIK - avatar