ts-transform-optional-chaining

A TypeScript custom transformer that enables optional chaining (aka existential operator, safe navigation) support in TypeScript via the non-null assertion operator.


Usage

With this plugin

``ts
foo!.bar!.baz
`

compiles to
`
foo && foo.bar && foo.bar.baz
`

so you can get that madness out of your code!




Requirement

TypeScript >= 2.4.1

How to use the custom transformer

Unfortunately, TypeScript itself does not currently provide any easy way to use custom transformers (See https://github.com/Microsoft/TypeScript/issues/14419).
The followings are the example usage of the custom transformer.

$3

`js
// webpack.config.js
const optionalChainingTransformer = require('@builder.io/ts-transform-optional-chaining/transformer').default;

module.exports = {
// ...
module: {
rules: [
{
test: /\.ts$/,
loader: 'ts-loader', // or 'awesome-typescript-loader'
options: {
getCustomTransformers: program => ({
before: [
optionalChainingTransformer(program)
]
})
}
}
]
}
};

`

$3

`js
// rollup.config.js
import typescript from 'rollup-plugin-typescript2';
import optionalChainingTransformer from '@builder.io/ts-transform-optional-chaining/transformer';

export default {
// ...
plugins: [
typescript({ transformers: [service => ({
before: [ optionalChainingTransformer(service.getProgram()) ],
after: []
})] })
]
};

`

$3

See ttypescript's README for how to use this with module bundlers such as webpack or Rollup.

`json
// tsconfig.json
{
"compilerOptions": {
// ...
"plugins": [
{ "transform": "@builder.io/ts-transform-optional-chaining/transformer" }
]
},
// ...
}
`

$3

See test for detail.
You can try it with $ npm test.

`js
const ts = require('typescript');
const optionalChainingTransformer = require('@builder.io/ts-transform-optional-chaining/transformer').default;

const program = ts.createProgram([/ your files to compile /], {
strict: true,
noEmitOnError: true,
target: ts.ScriptTarget.ES5
});

const transformers = {
before: [optionalChainingTransformer(program)],
after: []
};
const { emitSkipped, diagnostics } = program.emit(undefined, undefined, undefined, false, transformers);

if (emitSkipped) {
throw new Error(diagnostics.map(diagnostic => diagnostic.messageText).join('\n'));
}
``

License

MIT

[npm-image]:https://img.shields.io/npm/v/@builder.io/ts-transform-optional-chaining/transformer.svg?style=flat
[npm-url]:https://npmjs.org/package/@builder.io/ts-transform-optional-chaining/transformer