null-safety

null-safety is class which supports accessing to properties null-safety, undefined-safety, type-safety, sequentially.

Usage no npm install needed!

<script type="module">
  import nullSafety from 'https://cdn.skypack.dev/null-safety';
</script>

README

null-safety

CircleCI Coverage Status

example：

const html = `
<html>
  <h1>this is a title</h1>
</html>
`;

const doc = new JSDOM(html).window.document;

const title = NullSafety.start(doc)
  .next(o => o.querySelector('h1'))
  .next(o => o.textContent)
  .resultAlty('title-for-failed');

console.log(title);
// output: this is a title

type-safety：

const title = NullSafety.start(doc)

  .next(o => o.querySelector('h1'))
  // return: HTMLHeadingElement | null

  .next(o => o.textContent)
  // argument: HTMLHeadingElement (not nullable *>_<)b!
  // return:   string | null

  .resultAlty('title-for-failed');
  // return: string (not nullable *>_<)b!

recommendation:

Use TypeScript & TypeScript compiler option: strictNullChecks(or strict)

{
  "compilerOptions": {
    "strictNullChecks": true,
  }
}

// or

{
  "compilerOptions": {
    "strict": true,
  }
}