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JavaScript array: Find all elements that appear more than n times
We have an array of Number/String literals that contains some repeated entries. Our job is to write a function that takes in a positive integer Number n and returns a subarray of all the elements that makes appearance more than or equal to the number n specified by the only argument.
Therefore, let's write the code for this function −
We will use a Map() to keep count of the frequency of elements and later return the elements that exceed the specified count. The code for this will be −
Example
const arr = [34, 6, 34, 8, 54, 7, 87, 23, 34, 6, 21, 6, 23, 4, 23];
const moreThan = (arr, num) => {
const creds = arr.reduce((acc, val) => {
let { map, res } = acc;
const count = map.get(val);
if(!count && typeof count !== 'number'){
map.set(val, 1);
}else if(num - count <= 1){
res.push(val);
} else {
map.set(val, count+1);
};
return {map, res};
}, {
map: new Map(),
res: []
});
return creds.res;
};
console.log(moreThan(arr, 3));Output
The output in the console will be −
[34, 6, 23]
Updated on: 31-Aug-2020
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