I have multidimensional array with strings:
const arr = [['a', 'b'], ['c', 'd'], ['d', 'a']]
How can i log to console all values that occur in all nested arrays more than 1 time? (For this example function should console.log 'a' and 'd').
Thanks for the help
You first flat the arr.Then remove duplicates from it using Set. And loop through it then compare lastIndexOf and indexOf
const arr = [['a', 'b'], ['c', 'd'], ['d', 'a']]
let flat = arr.toString().split(',');
[... new Set(flat)].forEach(a => {
if(flat.indexOf(a) !== flat.lastIndexOf(a)) console.log(a)
})
let findDupesInMDArray = (arr) => {
// flatten the array
const flat = arr.flat();
// filter for dupes
return flat.filter((item, index) => flat.indexOf(item) != index)
}
let array = [['a', 'b'], ['c', 'd'], ['d', 'a']]
const dupes = findDupesInMDArray(array)
console.log(dupes)Using spread syntax, Array#flat, Array#reduce, Array#filter and Array#map.
const arr = [['a', 'b'], ['c', 'd'], ['d', 'a']]
const res = Array.from(arr.flat().reduce((a,c)=>{
return a.set(c, (a.get(c)||0) + 1);
}, new Map()))
.filter(([,c])=> c > 1)
.map(([k])=>k);
console.log(res);You could count the items by using a Map and get only the items with a count greater than one.
const
count = (m, a) => Array.isArray(a) ? a.reduce(count, m) : m.set(a, (m.get(a) || 0) + 1);
var array = [['a', 'b'], ['c', 'd'], ['d', 'a']],
result = Array
.from(array.reduce(count, new Map), ([k, v]) => v > 1 && k)
.filter(Boolean)
console.log(result);Here's a more basic approach:
var array = [['a', 'b'], ['c', 'd'], ['d', 'a']]
var result = [];
for (var i in array){
for (var l in array[i]){
if(array[i][l]==='a'||array[i][l]==='d')
result.push(array[i][l])
}}
var unique = new Set(result) //creates a set with unique values
console.log(unique) //should log the set {'a','d'}
What we're doing here is
console.logthem. I can create a fiddle if you need