String

T parameter &T parameter &mut T parameter T return value Option<T> parameter Option<T> return value JavaScript representation
Yes No No Yes Yes Yes JavaScript string value

Copies the string's contents back and forth between the JavaScript garbage-collected heap and the Wasm linear memory with TextDecoder and TextEncoder

Example Rust Usage


# #![allow(unused_variables)]
#fn main() {
use wasm_bindgen::prelude::*;

#[wasm_bindgen]
pub fn take_string_by_value(x: String) {}

#[wasm_bindgen]
pub fn return_string() -> String {
    "hello".into()
}

#[wasm_bindgen]
pub fn take_option_string(x: Option<String>) {}

#[wasm_bindgen]
pub fn return_option_string() -> Option<String> {
    None
}

#}

Example JavaScript Usage

import {
  take_string_by_value,
  return_string,
  take_option_string,
  return_option_string,
} from './guide_supported_types_examples';

take_string_by_value('hello');

let s = return_string();
console.log(typeof s); // "string"

take_option_string(null);
take_option_string(undefined);
take_option_string('hello');

let t = return_option_string();
if (t == null) {
  // ...
} else {
  console.log(typeof s); // "string"
}