Enable "strictNullChecks" option for TS definitions

A clean version of joint 2.1.0, obtained by running npm i jointjs, results in the following TypeScript errors: (2062,38): Type 'undefined' does not satisfy the constraint 'Model'. (2092,38): Type 'undefined' does not satisfy the constraint 'Model'.

Replacing mvc.View<undefined> by mvc.View<Backbone.Model> seems to fix it, but I can imagine undefined being a more concrete implementation of Backbone.Model. How should I fix this?

[zuozhiw]

@swenmeeuwes In tsconfig.json, you can set "skipLibCheck": true to let Typescript skip checking the libraries in strict mode, and you can add back "strictNullChecks": true, or maybe even "strict": true.

One suggestion to JointJS Typescript declarations regarding strictNullChecks in Typescript. Some of the type declarations are not strict. For example: getCell(id: string | number | Cell): Cell; But when the id doesn’t exist, this function returns undefined, so it’s better to write getCell(id: string | number | Cell): Cell | undefined;

[swenmeeuwes]

Hi vtalas,

First I stripped down my project to only use TypeScript en JointJs. After still getting the error I compared my project with the demo project and spotted a difference in tsconfig.json.

This line was the villain: "strictNullChecks": true,

Setting it to ‘false’ fixed the issue. Although I’d rather leave this setting on for code safety reasons.

Is there going to be support for this in the future? To reproduce you can just use the ts-demo and add "strictNullChecks": true to the tsconfig.json.