I'm a little stuck on a JavaScript function that can extract common numbers from a nested array of numbers.
Example input:
[[7, 3, 6, 10], [9, 10, 3], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]];
Expected output:
[3, 10]; // because 3 and 10 are present in all 3 arrays
It must work with any arbitrary array of numbers of any size.
Ideas?
You can do something like this:
var arr = [[7, 3, 6, 10], [9, 10, 3], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]];
var result = arr.shift().filter(function(v) {
return arr.every(function(a) {
return a.indexOf(v) !== -1;
});
});
console.log(result);It might pay to convert the inner arrays into ever shrinking Sets:
const arr = [[7, 3, 6, 10], [9, 10, 3], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]];
// Expected output: [3, 10]; // because 3 and 10 are present in all 3 arrays
let final = new Set(arr[0])
for ( i=1; i < arr.length ; i++) {
final = new Set (arr[i].filter ( x => final.has(x) ))
}
const newArr = Array.from(final)
console.log(newArr)var arrays = [[7, 3, 6, 10], [9, 10, 3], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]];
var result = arrays.shift().reduce(function(res, v) {
if (res.indexOf(v) === -1 && arrays.every(function(a) {
return a.indexOf(v) !== -1;
})) res.push(v);
return res;
}, []);
document.write('<pre>' + JSON.stringify(result,null,4)+ '</pre>');