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

user_17540080 0
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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

javascript
4 Answers

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);

user_95131840

If you know that the element is nth 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).

user_45548830

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);

user_74942180

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))

user_148071110
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