I have the following array
var array = [["ABC", "123"], ["DEF", "456"];
How can I get "123", if I look for "ABC? I tried
array["ABC"][1] //Want Output: 123
array["DEF"][1] //Want Output: 456
-
1Why don't you use an object?Unmitigated– Unmitigated2020-07-21 15:05:16 +00:00Commented Jul 21, 2020 at 15:05
Add a comment
|
5 Answers
You can use Array#find.
var array = [["ABC", "123"], ["DEF", "456"]];
let abc = array.find(x=>x[0]==="ABC");
console.log(abc?.[1]);
let def = array.find(x=>x[0]==="DEF");
console.log(def?.[1]);
let nothing = array.find(x=>x[0]==="NOTHING");
console.log(nothing?.[1]);However, using an object or Map is much better suited to this purpose. You can convert your array to an object using Object.fromEntries.
var array = [["ABC", "123"], ["DEF", "456"]];
const obj = Object.fromEntries(array);
console.log(obj.ABC);
console.log(obj['DEF']);You can pass the array to the Map constructor as well. Maps are better if you always want to retain insertion order.
var array = [["ABC", "123"], ["DEF", "456"]];
const map = new Map(array);
console.log(map.get("ABC"));
console.log(map.get("DEF"));Comments
You can use find to locate the item with the value at index 0. If you found, return the value at index 1.
const findByFirstValue = (arr, val) =>
((res) => res ? res[1] : null)(arr.find(v => v[0] === val))
console.log(findByFirstValue([["ABC", "123"], ["DEF", "456"]], 'ABC')).as-console-wrapper { top: 0; max-height: 100% !important; }
Comments
You can use map
const array = [["ABC", "123"], ["DEF", "456"]];
const newMap = new Map();
array.map(item=>{
newMap[item[0]] = item;
})
console.log(newMap['ABC'][1]);
2 Comments
Nick Parsons
Using
.map() for its looping functionality isn't what .map() is supposed to be used for. You want to use .forEach() if you're not going to use the output of .map(), or, instead, pass the Map constructor a mapped array: const newMap = new Map(array.map(([k, arr]) => [k, [k, arr]]))Nick Parsons
Also, to add entries to a
Map you want to use .set() rather than bracket notation, as this will add keys/values to the underlying object, and not to the Map (you can read more here)what you are trying to do is impossible using array, you are not allowed to use:
array["ABC"]
since array's indexing is number based, you need to use objects in order to get what you want:
var array = {"ABC": ["123", "789"], "DEF": ["456", "323"]};
now you are able to select them as you want:
array['ABC'][1] // 123
Comments
you can use index to get a value from array in
//first level
// array[0] =>["ABC", "123"]
// array[1] => ["DEF", "456"]
//second level
// array[0][0]=> "ABC"
// array[0][1]=> "123"
also you can use methods like map or foreach
