Create getPrimeNumbers.js

Author: Defite

getPrimeNumbers.js

@@ -0,0 +1,92 @@
+/**
+*
+* Get prime numbers (all or till some number)
+* https://youtu.be/s8zUK5jmXA4
+*/
+// O(n2)
+const isPrimeNumber = (num) => {
+  for (let i = 2, max = Math.sqrt(num); i <= max; i++) {
+    if (num % i === 0) {
+      return false;
+    }
+  }
+  return num > 1;
+}
+
+const getPrimeNumbers = (limit) => {
+  const numbers = [];
+  
+  for (let i = 2; i <= limit; i++) {
+    if (isPrimeNumber(i)) {
+      numbers.push(i);
+    }
+  }
+  
+  return numbers;
+}
+
+//const isPrimeNumber = (num) => {
+  for (let i = 2, max = Math.sqrt(num); i <= max; i++) {
+    if (num % i === 0) {
+      return false;
+    }
+  }
+  return num > 1;
+}
+
+const getPrimeNumbers = (limit) => {
+  const numbers = [];
+  
+  for (let i = 2; i <= limit; i++) {
+    if (isPrimeNumber(i)) {
+      numbers.push(i);
+    }
+  }
+  
+  return numbers;
+}
+
+// isPrimeNumbers(200);
+// [ 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199 ]
+
+const getPrimeNumbers2 = (limit) => {
+  const temp = [];
+  const numbers = [];
+  
+  for (let i=2; i < limit; i++) {
+    if (!temp[i]) {
+      numbers.push(i);
+      
+      for (let j = i * 2; j <= limit; j += i) {
+        temp[j] = true;
+      }
+    }
+  }
+  
+  return numbers;
+}
+
+getPrimeNumbers2(200)
+
+
+// O(loglogn)
+// "sieve of Eratosthenes"
+const getPrimeNumbers2 = (limit) => {
+  const temp = [];
+  const numbers = [];
+  
+  for (let i=2; i < limit; i++) {
+    if (!temp[i]) {
+      numbers.push(i);
+      
+      for (let j = i * 2; j <= limit; j += i) {
+        temp[j] = true;
+      }
+    }
+  }
+  
+  return numbers;
+}
+
+//getPrimeNumbers2(200)
+//[ 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199 ]