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JavaScript: Filter out the non-unique values in an array

JavaScript fundamental (ES6 Syntax): Exercise-22 with Solution

Write a JavaScript program to filter out the non-unique values in an array.

  • Use new Set() and the spread operator (...) to create an array of the unique values in arr.
  • Use Array.prototype.filter() to create an array containing only the unique values.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const filter_Non_Unique = arr => arr.filter(i => arr.indexOf(i) === arr.lastIndexOf(i));

console.log(filter_Non_Unique([1, 2, 2, 3, 4, 4, 5]));  
console.log(filter_Non_Unique([1, 2, 3, 4]));  

Sample Output:

[1,3,5]
[1,2,3,4]

Pictorial Presentation:

JavaScript Fundamental: Filter out the non-unique values in an array

Flowchart:

flowchart: Filter out the non-unique values in an array

Live Demo:

See the Pen javascript-basic-exercise-1-22 by w3resource (@w3resource) on CodePen.


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Next: Write a JavaScript program to filter out the non-unique values in an array, based on a provided comparator function.

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JavaScript: Tips of the Day

Returns an array of n-tuples of consecutive elements

Example:

const tips_arr = (n, arr) =>  n > arr.length ? [] : arr.slice(n - 1).map((v, i) =>[...arr.slice(i, i + n - 1), v]);
console.log(tips_arr(2, [1, 2, 3, 4, 5])); 
console.log(tips_arr(3, [1, 2, 3, 4, 5]));
console.log(tips_arr(5, [1, 2, 3, 4]));

Output:

[[1, 2], [2, 3], [3, 4], [4, 5]]
[[1, 2, 3], [2, 3, 4], [3, 4, 5]]
[]