17 lines
599 B
Markdown
17 lines
599 B
Markdown
### primes
|
|
|
|
Generates primes up to a given number, using the Sieve of Eratosthenes.
|
|
|
|
Generate an array from `2` to the given number. Use `Array.filter()` to filter out the values divisible by any number from `2` to the square root of the provided number.
|
|
|
|
```js
|
|
const primes = num => {
|
|
let arr = Array.from({length: num - 1}).map((x, i) => i + 2),
|
|
sqroot = Math.floor(Math.sqrt(num)),
|
|
numsTillSqroot = Array.from({length: sqroot - 1}).map((x, i) => i + 2);
|
|
numsTillSqroot.forEach(x => arr = arr.filter(y => ((y % x) !== 0) || (y == x)));
|
|
return arr;
|
|
};
|
|
// primes(10) -> [2,3,5,7]
|
|
```
|