@builder.io/ts-transform-optional-chaining
v0.0.4
Published
Optional chaining (aka existential operator, safe navigation) support in TypeScript via the non-null assertion operator
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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
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.
webpack (with ts-loader or awesome-typescript-loader)
// 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)
]
})
}
}
]
}
};
Rollup (with rollup-plugin-typescript2)
// 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: []
})] })
]
};
ttypescript
See ttypescript's README for how to use this with module bundlers such as webpack or Rollup.
// tsconfig.json
{
"compilerOptions": {
// ...
"plugins": [
{ "transform": "@builder.io/ts-transform-optional-chaining/transformer" }
]
},
// ...
}
TypeScript API
See test for detail.
You can try it with $ npm test
.
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