String - startsWith/substring/indexOf

Author: elpiel

src/js.rs

@@ -341,19 +341,41 @@ extern {
     #[wasm_bindgen(js_name = JsString)]
     pub type JsString;
 
+    /// The String object's charAt() method returns a new string consisting of the single
+    /// UTF-16 code unit located at the specified offset into the string.
+    ///
+    /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/charAt
+    #[wasm_bindgen(method, js_class = "String", js_name = charAt)]
+    pub fn char_at(this: &JsString, index: u32) -> JsString;
+
+    /// 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.
+    ///
+    /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/indexOf
+    #[wasm_bindgen(method, js_class = "String", js_name = indexOf)]
+    pub fn index_of(this: &JsString, search_value: &JsString, from_index: i32) -> i32;
+
     /// The slice() method extracts a section of a string and returns it as a
     /// new string, without modifying the original string.
     ///
     /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice
     #[wasm_bindgen(method, js_class = "String")]
     pub fn slice(this: &JsString, start: u32, end: u32) -> JsString;
 
-    /// The String object's charAt() method returns a new string consisting of the single
-    /// UTF-16 code unit located at the specified offset into the string.
+    /// The startsWith() method determines whether a string begins with the characters
+    /// of a specified string, returning true or false as appropriate.
     ///
-    /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/charAt
-    #[wasm_bindgen(method, js_class = "String", js_name = charAt)]
-    pub fn char_at(this: &JsString, index: u32) -> JsString;
+    /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/startsWith
+    #[wasm_bindgen(method, js_class = "String", js_name = startsWith)]
+    pub fn starts_with(this: &JsString, search_string: &JsString, position: u32) -> bool;
+
+    /// The substring() method returns the part of the string between the start and end indexes,
+    /// or to the end of the string.
+    ///
+    /// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substring
+    #[wasm_bindgen(method, js_class = "String")]
+    pub fn substring(this: &JsString, index_start: u32, index_end: u32) -> JsString;
 }
 
 impl<'a> From<&'a str> for JsString {

tests/all/js_globals/JsString.rs

@@ -59,3 +59,112 @@ fn slice() {
         "#)
         .test()
 }
+
+#[test]
+fn starts_with() {
+    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_starts_with(this: &js::JsString, search_string: &js::JsString, position: u32) -> bool {
+                this.starts_with(search_string, position)
+            }
+        "#)
+        .file("test.ts", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                let str = "To be, or not to be, that is the question.";
+
+                // TODO: remove second parameter for both assertions once we have optional parameters
+                assert.ok(wasm.string_starts_with(str, 'To be', 0));
+                assert.ok(!wasm.string_starts_with(str, 'not to be', 0));
+                assert.ok(wasm.string_starts_with(str, 'not to be', 10));
+            }
+        "#)
+        .test()
+}
+
+#[test]
+fn substring() {
+    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_substring(this: &js::JsString, index_start: u32, index_end: u32) -> js::JsString {
+                this.substring(index_start, index_end)
+            }
+        "#)
+        .file("test.ts", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                let anyString = "Mozilla";
+
+                assert.equal(wasm.string_substring(anyString, 0, 1), 'M');
+                assert.equal(wasm.string_substring(anyString, 1, 0), 'M');
+
+                assert.equal(wasm.string_substring(anyString, 0, 6), 'Mozill');
+
+                // TODO: Add test once we have optional parameters
+                // assert.equal(wasm.string_substring(anyString, 4), 'lla');
+                assert.equal(wasm.string_substring(anyString, 4, 7), 'lla');
+                assert.equal(wasm.string_substring(anyString, 7, 4), 'lla');
+
+                assert.equal(wasm.string_substring(anyString, 0, 7), 'Mozilla');
+                assert.equal(wasm.string_substring(anyString, 0, 10), 'Mozilla');
+            }
+        "#)
+        .test()
+}
+
+#[test]
+fn index_of() {
+    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_index_of(this: &js::JsString, search_value: &js::JsString, from_index: i32) -> i32 {
+                this.index_of(search_value, from_index)
+            }
+        "#)
+        .file("test.ts", r#"
+            import * as assert from "assert";
+            import * as wasm from "./out";
+
+            export function test() {
+                let str = "Blue Whale";
+
+                // TODO: remove second parameter once we have optional parameters
+                assert.equal(wasm.string_index_of(str, 'Blue', 0), 0);
+                // TODO: remove second parameter once we have optional parameters
+                assert.equal(wasm.string_index_of(str, 'Blute', 0), -1);
+                assert.equal(wasm.string_index_of(str, 'Whale', 0), 5);
+                assert.equal(wasm.string_index_of(str, 'Whale', 5), 5);
+                assert.equal(wasm.string_index_of(str, 'Whale', 7), -1);
+                // TODO: remove second parameter once we have optional parameters
+                assert.equal(wasm.string_index_of(str, '', 0), 0);
+                assert.equal(wasm.string_index_of(str, '', 9), 9);
+                assert.equal(wasm.string_index_of(str, '', 10), 10);
+                assert.equal(wasm.string_index_of(str, '', 11), 10);
+            }
+        "#)
+        .test()
+}