1 files changed, 48 insertions, 0 deletions
diff --git a/utils.mjs b/utils.mjs
new file mode 100644
index 0000000..61e61b1
--- /dev/null
+++ b/utils.mjs
@@ -0,0 +1,48 @@
+function randomItem(array) {
+    return array[Math.floor(Math.random() * array.length)]
+}
+
+function ordinalSuffix(v) {
+    let n = Number(v)
+    if (n > 20) {
+	n = n % 10
+    }
+
+    switch (n) {
+    case 1:
+	return 'st'
+    case 2:
+        return 'nd'
+    case 3:
+        return 'rd'
+    default:
+        return 'th'
+    }
+}
+
+function testOrdinalSuffix() {
+    const tests = {1: 'st',
+                   2: 'nd',
+                   3: 'rd',
+                   4: 'th',
+                   10: 'th',
+                   11: 'th',
+                   12: 'th',
+                   13: 'th',
+                   14: 'th',
+                   20: 'th',
+                   21: 'st',
+                   32: 'nd',
+                   43: 'rd',
+                   44: 'th',
+                   100: 'th',
+                   101: 'st'}
+    for (const t of Object.keys(tests)) {
+        const got = ordinalSuffix(t)
+        const want = tests[t]
+        console.assert(got === want,
+                       `bad suffix for ${t}: ${got} !== ${want}`)
+    }
+}
+
+export { ordinalSuffix, testOrdinalSuffix, randomItem }