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Counting the occurrences of JavaScript array elements and put in a new 2d array
We are required to write a JavaScript function that takes in an array of literal values. The function should then count the frequency of each element of the input array and prepare a new array on that basis.
For example − If the input array is −
const arr = [5, 5, 5, 2, 2, 2, 2, 2, 9, 4];
Then the output should be −
const output = [ [5, 3], [2, 5], [9, 1], [4, 1] ];
Example
The code for this will be −
const arr = [5, 5, 5, 2, 2, 2, 2, 2, 9, 4];
const frequencyArray = (arr = []) => {
const res = [];
arr.forEach(el => {
if (!this[el]) {
this[el] = [el, 0];
res.push(this[el])
};
this[el][1] ++
}, {});
return res;
};
console.log(frequencyArray(arr));Output
And the output in the console will be −
[ [ 5, 3 ], [ 2, 5 ], [ 9, 1 ], [ 4, 1 ] ]
Updated on: 24-Nov-2020
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