shared rng function

app/src/shared/utils.ts

@@ -6,4 +6,17 @@ export function countChar(str: string, char: string): number {
 // Generate a 6 character random ID
 export function randomId(): string {
     return Math.random().toString(36).slice(7)
+}
+
+// rng(1, 5) #=> result can be 1 2 3 4 or 5
+// rng(2)    #=> result can be 1 or 2
+export function rng(min: number, max = 0) {
+    if (max === 0) {
+        max = min
+        min = 1
+    }
+
+    min = Math.ceil(min)
+    max = Math.floor(max)
+    return Math.floor(Math.random() * (max - min + 1)) + min
 }