add bindings for array.prototype.some() (#341)

following the example set in https://github.com/rustwasm/wasm-bindgen/pull/314

src/js.rs

@@ -205,6 +205,13 @@ extern {
     #[wasm_bindgen(method)]
     pub fn slice(this: &Array, start: u32, end: u32) -> Array;
 
+    /// The some() method tests whether at least one element in the array passes the test implemented
+    /// by the provided function.
+    /// Note: This method returns false for any condition put on an empty array.
+    /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some
+    #[wasm_bindgen(method)]
+    pub fn some(this: &Array, predicate: &mut FnMut(JsValue) -> bool) -> bool;
+
     /// The sort() method sorts the elements of an array in place and returns
     /// the array. The sort is not necessarily stable. The default sort
     /// order is according to string Unicode code points.

tests/all/js_globals/Array.rs

@@ -143,6 +143,37 @@ fn sort() {
         .test()
 }
 
+#[test]
+fn some() {
+    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 has_elem(array: &js::Array, arg: JsValue) -> bool {
+                array.some(&mut |elem| arg == elem)
+            }
+
+        "#)
+        .file("test.ts", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                let elements = ["z", 1, "y", 2];
+
+                assert.deepStrictEqual(wasm.has_elem(elements, 2), true);
+                assert.deepStrictEqual(wasm.has_elem(elements, "y"), true);
+                assert.deepStrictEqual(wasm.has_elem(elements, "not an element"), false);
+            }
+        "#)
+        .test()
+}
+
 #[test]
 fn last_index_of() {
     project()