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问题:

I'm trying to use export and import but it not working I get an error

Here is my code HTML :

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
    @RenderBody()

    <script src="~/scripts/user.js"></script>
    <script src="~/scripts/main.js"></script>
</body>
</html>

User.ts :

export class User {
    firstName: string;
    lastName: string;
}

main.ts

import { User } from "./user";

Here is also screenshot of exception :

回答1:

You have a couple of options:

Option 1: Use a module loader like Webpack, Browserify, etc.

Option 2: If you just want to compile *.ts to *.js without any module imports or exports, set compilerOptions.module to "none" in your tsconfig.json. Note that you won't be able to export/import modules when you set compilerOptions.module to "none".

回答2:

try the following changes

HTML:

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
    @RenderBody()

    <!-- <script src="~/scripts/user.js"></script> --> <!-- not longer needed -->
    <script src="~/scripts/main.js"></script>
</body>
</html>

tsconfig.json

{
  "compilerOptions": {
    "module": "commonjs",
    "target": "es5",
    "sourceMap": true,
    "outFile": "~/scripts/main.js",
    "lib": [
      "dom",
      "es2015",
      "es5",
      "es6"
    ]
  }
}

with this config your output is only one js file what can be uglified wunderfull, containing all referenced files in the main.ts. i just don't know if ~/ works or if you have to set the path relative to the config file, i'm not working with linux.

User.ts

class User {
    firstName: string;
    lastName: string;
}

Main.ts:

/// <reference path="User.ts" />

// import { User } from "./user"; // not needed if referenced
console.log(new User());

all reference declarations have to be written at the beginning of the file

回答3:

TypeScript by default uses node module resolution. Node.js / CommonJS uses exports keyword. However, CommonJS doesn't run in browser without a module loader or module bundler. Hence, you need browserify or webpack to get it running in browser.

Check out this link https://www.typescriptlang.org/docs/handbook/gulp.html

You can also set module setting to none in compiler options section in tsconfig.json:

{ "compilerOptions": { "target": "es5", "module": "none" } }