JavaScript Powtórzenie elementu w tablicy
Array(5).fill(2)
//=> [2, 2, 2, 2, 2]
Inexpensive Ibis
Array(5).fill(2)
//=> [2, 2, 2, 2, 2]Array(5).fill(2)
//=> [2, 2, 2, 2, 2]
var names = ['Mike', 'Matt', 'Nancy', 'Adam', 'Jenny', 'Nancy', 'Carl']
var uniq = names
.map((name) => {
return {
count: 1,
name: name
}
})
.reduce((a, b) => {
a[b.name] = (a[b.name] || 0) + b.count
return a
}, {})
var duplicates = Object.keys(uniq).filter((a) => uniq[a] > 1)
console.log(duplicates) // [ 'Nancy' ]let a = [1, 2, 3, 4, 2, 2, 4, 1, 5, 6]
let b = [...new Set(a.sort().filter((o, i) => o !== undefined && a[i + 1] !== undefined && o === a[i + 1]))]
// b is now [1, 2, 4]