打字稿|TypeError:__WEBPACK_IMPORTED_MODULE_1_signature_pad__不是构造函数 [英] Typescript | TypeError: __WEBPACK_IMPORTED_MODULE_1_signature_pad__ is not a constructor

问题描述

我目前正在从事Angular2项目，并且正在尝试使用JS库( https://github.com/szimek/signature_pad )进行签名输入.

I'm currently working on an Angular2 project and I'm trying to use a JS library (https://github.com/szimek/signature_pad) for signature input.

我尝试按原样使用该库，其代码如下:

I've tried using the library as is, with my code as follows:

// .ts file
import * as SignaturePad from 'signature_pad';

export class ... {
    private signaturePad: SignaturePad;

    ngOnInit() {
        let canvas = document.querySelector("canvas");
        this.signaturePad = new SignaturePad(canvas);
    }
}

.

// .html file
<div...>
    <canvas></canvas>
</div>

，启动浏览器页面时出现以下错误:错误错误:未被捕获(承诺):TypeError: WEBPACK_IMPORTED_MODULE_1_signature_pad 不是构造函数

and I get the following error when I launch the browser page: ERROR Error: Uncaught (in promise): TypeError: WEBPACK_IMPORTED_MODULE_1_signature_pad is not a constructor

我也尝试过使用dimpu的angular2-signature-pad，但实际上会出现相同的错误.

I've also tried using dimpu's angular2-signature-pad, but the same error essentially comes up.

推荐答案

假定您具有 signature_pad 的类型( npm install --save-dev @ types/signature_pad )，则必须像下面这样导入和使用它，因为 signature_pad 没有任何导出的成员，而仅将 SignaturePad 类声明到当前作用域中:

Provided you have the typings for signature_pad (npm install --save-dev @types/signature_pad), it has to be imported and used like below as signature_pad does not have any exported members and only declares the class SignaturePad into the current scope:

import 'signature_pad';

// ...
let canvas = document.querySelector("canvas");
this.signaturePad = new SignaturePad(canvas);

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