Provide an API to convert tsconfig.json to CompilerOptions

[IgorMinar]

Since IDEs like VS Code use tsconfig.json to figure out how to parse a project, it makes sense for all the other build tools (gulp, broccoli, webpack, etc) to pull the tsc config from tsconfig.json as well, instead of having their own custom way to configure tsc.

In order for this to be seamless, Typescript needs to provide a way to parse tsconfig.json to CompilerOptions object. tsc already does this internally, but all of the apis it uses are private.

I've put together my own converter for Angular/broccoli-typescript, but it will get stale with the next version of typescript until I update my option mappings. See ts-config-converter.ts added in angular/angular#4779

I believe that this task is so common that it should be part of typescripts public api.

cc: @alexeagle

[mhegazy]

here you go: https://github.com/Microsoft/TypeScript/blob/master/lib/typescript.d.ts#L1536-L1555

use ts.parseConfigFile to parse the text. if you want to parse the JSON the same way as the compiler does as well (currently using JSON.parse, but possibly in the future do something more interesting allowing comments for instance) use ts.parseConfigFileText

[IgorMinar]

Awesome. That's what I need.

Is the filename option significant? We also have a use case where the configuration is an object already in the tsconfig format, so I would just serialize it and pass it in as text with bogus filename. Will there be any problems with that?

[mhegazy]

in parseConfigFileTextToJson the name is used only for the error message.
https://github.com/Microsoft/TypeScript/blob/master/src/compiler/commandLineParser.ts#L401

in parseJsonConfigFileContent basePath is expected to be the location of the tscongfig, as all files path in the options are considered relative to the file location.
https://github.com/Microsoft/TypeScript/blob/master/src/compiler/commandLineParser.ts#L416

[IgorMinar]

I tried using parseJsonConfigFileContent but it feels too heavyweight since it requires me to implement ParseConfigHost.

All I want is:

ts.convertConfigToCompilerOptions({
    emitDecoratorMetadata: true,
    experimentalDecorators: true,
    declaration: true,
    module: 'commonjs',
    moduleResolution: 'classic',
    noEmitOnError: true,
    rootDir: '.',
    sourceMap: true,
    sourceRoot: '.',
    target: 'es5'
})
=> CompilerOptions

Could that be a thing?

[vladima]

I don't see why not, we already have this code as nested function of parseJsonConfigFileContent.
Also as a temporary workaround for now you can use something like this

function convertConfigToCompilerOptions(opts) {
    var parsed = ts.parseJsonConfigFileContent({
        compilerOptions: opts,
        // if files are not specified then parseJsonConfigFileContent 
        // will use ParseConfigHost to collect files in containing folder
        files: []  
        },
        // we don't do any file lookups - host and base folders should not be used
        undefined, 
        undefined);
    return parsed.options;
}

[IgorMinar]

That worked! It's a bit awkward, but it works. Thanks Vladimir.

On Sat, Oct 17, 2015 at 4:49 PM Vladimir Matveev notifications@github.com
wrote:

I don't see why not, we already have this code as nested function of
parseJsonConfigFileContent.
Also as a temporary workaround for now you can use something like this

function convertConfigToCompilerOptions(opts) {
var parsed = ts.parseJsonConfigFileContent({
compilerOptions: opts,
// if files are not specified then parseJsonConfigFileContent
// will use ParseConfigHost to collect files in containing folder
files: []
},
// we don't do any file lookups - host and base folders should not be used
undefined,
undefined);
return parsed.options;
}

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[vladima]

@IgorMinar convertCompilerOptionsFromJson will be available in todays nightly build

[wycats]

@mhegazy @vladima This is getting pretty frustrating; it just broke again.

Here's what we had to do to get it working on typescript@next: tildeio/broccoli-typescript-compiler@ff874d9?w=1

Can you recommend a stable API we can use?

[wycats]

See also tildeio/broccoli-typescript-compiler#7.

We're very eager to get on a supported, stable path here, but can't seem to find one.

[vladima]

@wycats apologies, this breaking change was not intentional. I'll revert convertCompilerOptionsFromJson to the shape it used to be in 1.8