JavaScript: Get all possible subset with a fixed length combinations in an array
JavaScript Function: Exercise-21 with Solution
Write a JavaScript function to get all possible subset with a fixed length (for example 2) combinations in an array.
Sample array : [1, 2, 3] and subset length is 2
Expected output : [[2, 1], [3, 1], [3, 2], [3, 2, 1]]
Sample Solution: -
HTML Code:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>JavaScript array subset</title>
</head>
<body>
</body>
</html>
JavaScript Code:
function subset(arra, arra_size)
{
var result_set = [],
result;
for(var x = 0; x < Math.pow(2, arra.length); x++)
{
result = [];
i = arra.length - 1;
do
{
if( (x & (1 << i)) !== 0)
{
result.push(arra[i]);
}
} while(i--);
if( result.length >= arra_size)
{
result_set.push(result);
}
}
return result_set;
}
console.log(subset([1, 2, 3], 2));
Sample Output:
[[2,1],[3,1],[3,2],[3,2,1]]
Flowchart:

Live Demo:
See the Pen JavaScript - Get all possible subset with a fixed length combinations in an array-function-ex- 21 by w3resource (@w3resource) on CodePen.
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JavaScript: Tips of the Day
Shorten an array using its length property
A great way of shortening an array is by redefining its length property.
let array = [0, 1, 2, 3, 4, 5, 6, 6, 8, 9] array.length = 4 // Result: [0, 1, 2, 3]
Important to know though is that this is a destructive way of changing the array. This means you lose all the other values that used to be in the array.
Ref: https://bit.ly/2LBj213
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