add behavior JS

content/en/docs/programming/javascript/behavior.md

@@ -0,0 +1,39 @@
+---
+title: "Strange behavior"
+description: "Strange behavior of Javascript"
+lead: "Strange behavior of Javascript"
+date: 2023-01-01T00:00:00+00:00
+lastmod: 2023-01-01T00:00:00+00:00
+draft: false
+images: []
+menu:
+  docs:
+    parent: "javascript"
+weight: 620
+toc: true
+---
+
+## Uppercase
+
+Certain Unicode characters, when uppercased, actually expand in length.
+
+```js
+for (let i = 0; i < 0x10FFFF; i++) {
+	var c = String.fromCodePoint(i);
+	var upper = c.toUpperCase();
+	if (c.length !== upper.length)
+		console.log(i, c, c.length, upper, upper.length);
+}
+```
+
+```
+223 ß 1 SS 2
+329 ʼn 1 ʼN 2
+496 ǰ 1 J̌ 2
+912 ΐ 1 Ϊ́ 3
+944 ΰ 1 Ϋ́ 3
+1415 և 1 ԵՒ 2
+7830 ẖ 1 H̱ 2
+7831 ẗ 1 T̈ 2
+...
+```