JavaScript: Group the elements into two arrays, depending on the provided function's truthiness for each element
JavaScript fundamental (ES6 Syntax): Exercise-168 with Solution
Write a JavaScript program to group the elements into two arrays, depending on the provided function's truthiness for each element.
- Use Array.prototype.reduce() to create an array of two arrays.
- Use Array.prototype.push() to add elements for which fn returns true to the first array and elements for which fn returns false to the second one.
Sample Solution:
JavaScript Code:
//#Source https://bit.ly/2neWfJ2
const partition = (arr, fn) =>
arr.reduce(
(acc, val, i, arr) => {
acc[fn(val, i, arr) ? 0 : 1].push(val);
return acc;
},
[[], []]
);
const users = [{ user: 'barney', age: 36, active: false }, { user: 'fred', age: 40, active: true }];
partition(users, o => o.active);
console.log(users);
Sample Output:
[{"user":"barney","age":36,"active":false},{"user":"fred","age":40,"active":true}]
Flowchart:

Live Demo:
See the Pen javascript-basic-exercise-168-1 by w3resource (@w3resource) on CodePen.
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Previous: Write a JavaScript program to calculate how many numbers in the given array are less or equal to the given value using the percentile formula.
Next: Write a JavaScript program to create a function that invokes fn with partials appended to the arguments it receives.
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