How load an emscripten generated module in Vue.js in order to use its functions?

问题

As you can read here: https://forum.vuejs.org/t/wasm-how-to-correctly-call-a-webassembly-method-in-vue-js/83422/24 I'm trying to figure out how to import a module generated by emscripten in Vue.js in order to call its methods.

Following the indications found here: How load an emscripten generated module with es6 import? I compiled add.c with this command:

emcc add.c -o js_plumbing.js -s EXPORTED_FUNCTIONS="['_Add']" -s  
EXTRA_EXPORTED_RUNTIME_METHODS=['ccall','cwrap'] -s EXPORT_ES6=1 -s 
MODULARIZE=1

and modified Result.vue accordingly in this way:

<template>
  <div>
    <p button @click="callAdd">Add!</p>
    <p>Result: {{ result }}</p>
  </div>
</template>

<script>
    import Module  from './js_plumbing'
    const mymod = Module();
    export default {
      data () {
        return {
          result: null
        }
      },
      methods: {
        callAdd() {
          const result = mymod.cwrap('Add',
            'number',
            ['number', 'number'],
            [1, 2]);
          this.result = result;
        }
      }
    }
</script>

But I got this error:

Failed to compile.

./src/components/js_plumbing.js
Module build failed (from ./node_modules/babel-loader/lib/index.js):
SyntaxError: Unexpected token, expected ( (3:25)

  1 | 
  2 | var Module = (function() {
> 3 |   var _scriptDir = import.meta.url;
    |                          ^
  4 |   
  5 |   return (
  6 | function(Module) {

The only way I found to import emscripten generated Module and use its functions, is to use a sort of an "hack": manually adding 'export' keyword in the Module definition in js_plumbing_js, the javascript file generated by compiling add.c with:

emcc add.c -o js_plumbing.js -s EXTRA_EXPORTED_RUNTIME_METHODS=['ccall','cwrap'] -s 
ENVIRONMENT='web','worker'

Result.vue :

<template>
  <div>
    <p button @click="callAdd">Add!</p>
    <p>Result: {{ result }}</p>
  </div>
</template>

<script>
    import * as js_plumbing from './js_plumbing'
    import Module  from './js_plumbing'
    export default {
      data () {
        return {
          result: null
        }
      },
      methods: {
        callAdd () {
          const result = js_plumbing.Module.ccall('Add',
            'number',
            ['number', 'number'],
            [1, 2]);
          this.result = result;
        }
      }
    }
</script>

js_plumbing.js :

// Copyright 2010 The Emscripten Authors.  All rights reserved.
// Emscripten is available under two separate licenses, the MIT license and the
// University of Illinois/NCSA Open Source License.  Both these licenses can be
// found in the LICENSE file.

// The Module object: Our interface to the outside world. We import
// and export values on it. There are various ways Module can be used:
// 1. Not defined. We create it here
// 2. A function parameter, function(Module) { ..generated code.. }
// 3. pre-run appended it, var Module = {}; ..generated code..
// 4. External script tag defines var Module.
// We need to check if Module already exists (e.g. case 3 above).
// Substitution will be replaced with actual code on later stage of the build,
// this way Closure Compiler will not mangle it (e.g. case 4. above).
// Note that if you want to run closure, and also to use Module
// after the generated code, you will need to define   var Module = {};
// before the code. Then that object will be used in the code, and you
// can continue to use Module afterwards as well.
export var Module = typeof Module !== 'undefined' ? Module : {};

But, as I said, I do not like this manual hack. Any suggestions on how to make the Module exportable, thus importable, without manually adding ‘export’ in js_plumbing.js file?

1° Update)

Following the indications of the answer here: How to call a webassembly method in vue.js?

I compiled the add.c file in this way:

emcc add.c -o js_plumbing.js -s MODULARIZE=1

and then modified Result.vue as follows:

<template>
  <div>
    <p button @click="callAdd">Add!</p>
    <p>Result: {{ result }}</p>
  </div>
</template>

<script>
    import Module from './js_plumbing'
    export default {
      data () {
        return {
          result: null
        }
      },
      methods: {
        callAdd() {
          const instance = Module({
            onRuntimeInitialized() {
              console.log(instance._Add(1,2));
              this.result = instance._Add(1,2);
            }
          })
        }
      }
    }
</script>

There must be something I'm doing wrong, since I do get the console.log when clicking to the Add! button,but the output is not transferred to the the html part of Result.vue:

回答1:

import Module from './js_plumbing';

let instance = {
  ready: new Promise(resolve => {
    Module({
      onRuntimeInitialized () {
        instance = Object.assign(this, {
          ready: Promise.resolve()
        });
        resolve();
      }
    });
  })
};

export default {
  data () {
    return {
      result: null
    };
  },
  methods: {
    callAdd(a, b) {
      instance.ready
      .then(_ => this.result = instance._Add(a, b));
    }
  }
};

回答2:

An another excellent solution to the problem was found by Gerard Gallant, the author of the book "WebAssembly in action" : https://github.com/emscripten-core/emscripten/issues/10114

来源：https://stackoverflow.com/questions/59530889/how-load-an-emscripten-generated-module-in-vue-js-in-order-to-use-its-functions

标签

javascript

Vue.js

es6-modules

emscripten

webassembly