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问题:

I'm trying to play with Babel, but it doesn't work well for me.

My project is simple

|-project/
|---src/
|-----index.html
|-----main.js
|-----module.js
|---Gruntfile.js
|---package.json

index.html

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>Test</title>
    <script src="main.js" type="application/javascript"></script>
</head>
<body>
<p>Simple html file.</p>
</body>
</html>

main.js

import * as math from "./module";

async function anwser() {
    return 42;
}

(function main() {
    anwser().then((v) => {
        console.info(v);
    });

    console.log(math.sum(5, 5));
})();

module.js

export function sum(x, y) {
    return x + y;
}

Gruntfile.js

module.exports = function(grunt) {

    grunt.initConfig({
        "babel": {
            "options": {
                "sourceMap": true,
                "experimental": true
            },
            dist: {
                files: [{
                    "expand": true,
                    "cwd": "src/",
                    "src": ["**/*.js"],
                    "dest": "build/",
                    "ext": ".js"
                }]
            }
        },
        htmlmin: {
            dist: {
                options: {
                    removeComments: true,
                    collapseWhitespace: true
                },
                files: [{
                    "expand": true,
                    "cwd": "src/",
                    "src": ["**/*.html"],
                    "dest": "build/",
                    "ext": ".html"
                }]
            }
        },
        watch: {
            scripts: {
                files: 'src/*.js',
                tasks: ["babel"]
            },
            html: {
                files: 'src/*.html',
                tasks: ["htmlmin"]
            }
        }
    });

    grunt.loadNpmTasks('grunt-babel');
    grunt.loadNpmTasks('grunt-contrib-watch');
    grunt.loadNpmTasks('grunt-contrib-htmlmin');

    grunt.registerTask("default", ["babel", "htmlmin"]);
};

I run grunt, everything compile. But I can't use have the expected result.

First, the browser say require is not defined, so I add require.js to my HTML.

Then, I get Error: Module name "module" has not been loaded yet for context: _. Use require([]) http://requirejs.org/docs/errors.html#notloaded

I'm a bit confused about all of these. How I can make my code work?

回答1:

To expand on veg_prog's answer, you should use something like Browserify if you want to organize your code into modules. Browserify can be used with Grunt via grunt-browserify, and Babel can be used with Browserify via babelify.

I've tweaked some of your files to show you how it can be done:

index.html

<!DOCTYPE html>
<html>
<head lang="en">
  <meta charset="UTF-8">
  <title>Test</title>
  <script src="bundle.js" type="application/javascript"></script>
</head>
<body>
  <p>Simple html file.</p>
</body>
</html>

main.js

import "babelify/polyfill"; // Needed for Babel's experimental features.
import * as math from "./module";

async function anwser() {
  return 42;
}

(function main() {
  anwser().then((v) => {
    console.info(v);
  });

  console.log(math.sum(5, 5));
})();

Gruntfile.js

module.exports = function(grunt) {

  grunt.initConfig({
    browserify: {
      dist: {
        options: {
          transform: [["babelify", { "stage": 0 }]]
        },
        files: {
          "build/bundle.js": "src/main.js"
        }
      }
    },
    htmlmin: {
      dist: {
        options: {
          removeComments: true,
          collapseWhitespace: true
        },
        files: [{
          "expand": true,
          "cwd": "src/",
          "src": ["**/*.html"],
          "dest": "build/",
          "ext": ".html"
        }]
      }
    },
    watch: {
      scripts: {
        files: "src/*.js",
        tasks: ["browserify"]
      },
      html: {
        files: "src/*.html",
        tasks: ["htmlmin"]
      }
    }
  });

  grunt.loadNpmTasks("grunt-browserify");
  grunt.loadNpmTasks("grunt-contrib-watch");
  grunt.loadNpmTasks("grunt-contrib-htmlmin");

  grunt.registerTask("default", ["browserify", "htmlmin"]);
};

package.json

{
  "devDependencies": {
    "babelify": "6.0.1",
    "grunt": "0.4.5",
    "grunt-browserify": "3.6.0",
    "grunt-contrib-htmlmin": "0.4.0",
    "grunt-contrib-watch": "0.6.1"
  }
}

回答2:

Babel uses 'common' by default. That doesn't work for requirejs. So, change modules to 'amd'.

"babel": {
    "options": {
        "sourceMap": true,
        "experimental": true,
        "modules": "amd"        //This is the line to be added.
    },
    dist: {
        files: [{
            "expand": true,
            "cwd": "src/",
            "src": ["**/*.js"],
            "dest": "build/",
            "ext": ".js"
        }]
    }
}

Update for Babel6. See also http://babeljs.io/docs/plugins/transform-es2015-modules-amd/ and https://babeljs.io/docs/plugins/

"babel": {
    "options": {
        "sourceMap": true,
        "experimental": true,
        "plugins": ["transform-es2015-modules-amd"] //This is the line to be added.
    },
    dist: {
        files: [{
            "expand": true,
            "cwd": "src/",
            "src": ["**/*.js"],
            "dest": "build/",
            "ext": ".js"
        }]
    }
}

回答3:

First, the browser say require is not defined, so I add require.js to my HTML.

I don't think, that adding require.js will be the solution. In this context require is node-style syntax: (https://github.com/substack/browserify-handbook#user-content-require).

Browserify is a module loader but works different than requirejs. There is a babel distribution for requirejs, too (https://github.com/mikach/requirejs-babel) but I recommend using browserify.

In a setup, where babel is working with browserify, something like this