How to get a value of array of objects (pair key-value) in javascript?

Question

Good time, i have an array of objects like this:

var sections = [ {key: 0, label: 'Nothing'}, {key: 11, label: 'Alex Right'},{key: 12, label: 'Dolores Black'},{key: 21, label: 'Bobby Smith'},{key: 26, label: 'Andrew Small'} ];

So, for example, i want to get label that is for key=12 (it have to be Dolores Black). If i use something like:

alert(sections[11]['label']);

this will be wrong, cause it will find 12th element of array, not an element with key=12. So what is th right expression for my case? Thanks

Answer 1

Use Array#find :

 let sections = [ {key: 0, label: 'Nothing'}, {key: 11, label: 'Alex Right'},{key: 12, label: 'Dolores Black'},{key: 21, label: 'Bobby Smith'},{key: 26, label: 'Andrew Small'} ]; let res = sections.find(({key}) => key === 12)?.label; console.log(res);

Answer 2

If you know that the element is n ^th in the array, use sections[n - 1]['label'] ; for example, to get Dolores Black (the 3rd element), you'd do:

sections[2]['label']; // 3 - 1 = 2

If you don't know the position of the element beforehand, you have to give some condition to JavaScript, so that it can find it; in your case, the condition is item .key === 12 :

sections.find((item) => item.key === 12)['label'];

Note that in both cases we assume that the element actually exists in the array (if it doesn't, there will be errors).

Answer 3

The find() method which will return the value of the first element in the provided array that satisfies the provided testing function

 var sections = [ {key: 0, label: 'Nothing'}, {key: 11, label: 'Alex Right'},{key: 12, label: 'Dolores Black'},{key: 21, label: 'Bobby Smith'},{key: 26, label: 'Andrew Small'} ]; var res = sections.find(x => x.key === 12); console.log(res.label);

Answer 4

I would wrap this in a function. Inside function i use the js function find(). If you have more items with the same id then i would use filter instead find.

 const sections = [ {key: 0, label: 'Nothing'}, {key: 11, label: 'Alex Right'},{key: 12, label: 'Dolores Black'},{key: 21, label: 'Bobby Smith'},{key: 26, label: 'Andrew Small'} ]; const id = 11; function getLabel(id) { return sections.find(e => e.key === id)['label']; } console.log(getLabel(id))