Support String.prototype.codePointAt

src/js.rs

@@ -447,6 +447,12 @@ extern {
     #[wasm_bindgen(method, js_class = "String", js_name = charAt)]
     pub fn char_at(this: &JsString, index: u32) -> JsString;
 
+    /// The codePointAt() method returns a non-negative integer that is the Unicode code point value.
+    ///
+    /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/codePointAt
+    #[wasm_bindgen(method, js_class = "String", js_name = codePointAt)]
+    pub fn code_point_at(this: &JsString, pos: u32) -> JsValue;
+
     /// The indexOf() method returns the index within the calling String object of
     /// the first occurrence of the specified value, starting the search at fromIndex.
     /// Returns -1 if the value is not found.

tests/all/js_globals/JsString.rs

@@ -31,6 +31,34 @@ fn char_at() {
         .test()
 }
 
+#[test]
+fn code_point_at() {
+    project()
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section)]
+
+            extern crate wasm_bindgen;
+            use wasm_bindgen::prelude::*;
+            use wasm_bindgen::js;
+
+            #[wasm_bindgen]
+            pub fn string_code_point_at(this: &js::JsString, pos: u32) -> JsValue {
+                this.code_point_at(pos)
+            }
+        "#)
+        .file("test.ts", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                assert.equal(wasm.string_code_point_at('ABC', 1), 66);
+                assert.equal(wasm.string_code_point_at('\uD800\uDC00', 0), 65536);
+                assert.equal(wasm.string_code_point_at('XYZ', 42), undefined);
+            }
+        "#)
+        .test()
+}
+
 #[test]
 fn starts_with() {
     project()