What is the process of importing an IIFE-based JavaScript module into an Angular TypeScript application?

Question

What is the process of importing an IIFE-based JavaScript module into an Angular TypeScript application?

I have come across a third-party SDK that is structured as an oldschool IIFE based module. The code looks something like this:

var ThirdPartySDK = (function() {
  var export = {};

  // Adding some methods to export

  return export;
})();

To use this SDK, one would typically reference it on the global scope like so:

<html>
  <body>
    <script src="lib/ThirdPartySDK.js">
    <script>
      ThirdPartySDK.foo();
    <\script>
  <\body>
<\html>

While using it in this way is still possible, I am wondering if there is a better approach when working with Angular and TypeScript. Is there a way to configure angular/TypeScript/webpack environment to allow for proper import statements? Such as:

import { ThirdPartySDK } from '../lib/ThirdPartySDK.js';
ThirdPartySDK.foo();

javascript angular typescript webpack iife

Answer 1

Answer №1

To ensure a proper import statement for the actual value of ThirdPartySDK, it is recommended to refactor the script into a module that exports this value. The code snippet below demonstrates how you can achieve this:

export const ThirdPartySDK = {
    foo() { console.log('Doing foo'); }
};

For larger libraries, refactoring may not be straightforward. In such cases, consider the following two approaches which require minimal refactoring:

1. Export the ThirdPartySDK variable

You can convert the IIFE file into a module by exporting the current IThirdPartySDK variable and then import it as follows:

export const ThirdPartySDK = (function() {
    var _export = {};

    // Implement additional methods to export

    return _export;
})();

If you need information on the structure of ThirdPartySDK, add a type annotation to the const declaration. If SomeType is not defined, you will have to create it yourself:

export const ThirdPartySDK: SomeType = (function() {
// ...

To address any TypeScript errors related to assigning the IIFE expression to SomeType, use the as keyword:

export const ThirdPartySDK: SomeType = (function() {
    // ...
})() as SomeType;

2. Retain the <script> tag and declare the variable

An alternative approach is to keep the script tag, avoid importing anything, and declare the variable along with its expected type in TypeScript:

(You may need to provide the type definitions manually in this scenario)

interface SomeType {
    // Define SDK type structure here...
}

declare const ThirdPartySDK: SomeType;

Answer 2

To ensure a proper import statement for the actual value of ThirdPartySDK, it is recommended to refactor the script into a module that exports this value. The code snippet below demonstrates how you can achieve this:

export const ThirdPartySDK = {
    foo() { console.log('Doing foo'); }
};

For larger libraries, refactoring may not be straightforward. In such cases, consider the following two approaches which require minimal refactoring:

1. Export the ThirdPartySDK variable

You can convert the IIFE file into a module by exporting the current IThirdPartySDK variable and then import it as follows:

export const ThirdPartySDK = (function() {
    var _export = {};

    // Implement additional methods to export

    return _export;
})();

If you need information on the structure of ThirdPartySDK, add a type annotation to the const declaration. If SomeType is not defined, you will have to create it yourself:

export const ThirdPartySDK: SomeType = (function() {
// ...

To address any TypeScript errors related to assigning the IIFE expression to SomeType, use the as keyword:

export const ThirdPartySDK: SomeType = (function() {
    // ...
})() as SomeType;

2. Retain the <script> tag and declare the variable

An alternative approach is to keep the script tag, avoid importing anything, and declare the variable along with its expected type in TypeScript:

(You may need to provide the type definitions manually in this scenario)

interface SomeType {
    // Define SDK type structure here...
}

declare const ThirdPartySDK: SomeType;

Answer 3

Answer №2

To incorporate a third-party SDK into your TypeScript code, you can utilize a workaround involving the use of eval.

Consider the scenario where ThirdPartySDK.js has the following structure:

var ThirdPartySDK = (function () {
    var exports = {
        foo: function () { console.log("Hello, world!"); }
    };
    return exports;
})();

In this case, you would create a module called ThirdPartySDK-wrapper.ts with the following content:

import * as fs from 'fs';
const script = fs.readFileSync('../lib/ThirdPartySDK.js').toString();

global.eval(script);

//@ts-ignore
export default ThirdPartySDK;

The directive @ts-ignore is necessary to prevent TypeScript compiler errors related to the absence of a declaration for the ThirdPartySDK variable (which is declared within the eval-executed script).

You can then import and utilize ThirdPartySDK via the wrapper module:

import ThirdPartySDK from './wrapper';
ThirdPartySDK.foo();  // Outputs: "Hello, world!"

Please note that this approach is specifically tailored for Node.js applications as it relies on fs.fileReadSync to fetch the script contents.

If you intend to employ this in a browser environment, alternatives must be explored to retrieve the script. One possible solution could involve leveraging tools like WebPack to package the ThirdPartySDK script as a string value that can be imported using require within the wrapper module.

Answer 4

To incorporate a third-party SDK into your TypeScript code, you can utilize a workaround involving the use of eval.

Consider the scenario where ThirdPartySDK.js has the following structure:

var ThirdPartySDK = (function () {
    var exports = {
        foo: function () { console.log("Hello, world!"); }
    };
    return exports;
})();

In this case, you would create a module called ThirdPartySDK-wrapper.ts with the following content:

import * as fs from 'fs';
const script = fs.readFileSync('../lib/ThirdPartySDK.js').toString();

global.eval(script);

//@ts-ignore
export default ThirdPartySDK;

The directive @ts-ignore is necessary to prevent TypeScript compiler errors related to the absence of a declaration for the ThirdPartySDK variable (which is declared within the eval-executed script).

You can then import and utilize ThirdPartySDK via the wrapper module:

import ThirdPartySDK from './wrapper';
ThirdPartySDK.foo();  // Outputs: "Hello, world!"

Please note that this approach is specifically tailored for Node.js applications as it relies on fs.fileReadSync to fetch the script contents.

If you intend to employ this in a browser environment, alternatives must be explored to retrieve the script. One possible solution could involve leveraging tools like WebPack to package the ThirdPartySDK script as a string value that can be imported using require within the wrapper module.

What is the process of importing an IIFE-based JavaScript module into an Angular TypeScript application?

Answer №1

Answer №2

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