javascript check if array has duplicates
function hasDuplicates(array) {
return (new Set(array)).size !== array.length;
}javascript check if array has duplicates
function hasDuplicates(array) {
return (new Set(array)).size !== array.length;
}check for duplicates in array javascript
[1, 2, 3].every((e, i, a) => a.indexOf(e) === i) // true
[1, 2, 1].every((e, i, a) => a.indexOf(e) === i) // falsehow to count duplicates in an array javascript
arr.reduce((b,c)=>((b[b.findIndex(d=>d.el===c)]||b[b.push({el:c,count:0})-1]).count++,b),[]);Find duplicate or repeat elements in js array
const a = [4,3,6,3,4,3]
function count_duplicate(a){
let counts = {}
for(let i =0; i < a.length; i++){
if (counts[a[i]]){
counts[a[i]] += 1
} else {
counts[a[i]] = 1
}
}
for (let prop in counts){
if (counts[prop] >= 2){
console.log(prop + " counted: " + counts[prop] + " times.")
}
}
console.log(counts)
}
count_duplicate(a)Copyright © 2021 Codeinu
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