Compiler API: Creating a TypeNode from a string?

[ffMathy]

In TypeScript, how can I turn the string { [index: string]: { foo: string } } into a TypeNode in the compiler API? Is that possible?

I already tried doing this by creating a "file" and putting the contents into it and parsing it, but that doesn't seem to be creating a TypeNode.

Any ideas?

[ajafff]

I usually create a string with a variable declaration with the type I want to parse and parse it as a SourceFile:

ts.createSourceFile('tmp.ts', `let a:${type}`).statements[0].declarationList.declarations[0].type;

[ffMathy]

Is there a cleaner way to do it? I think that feels pretty dirty.

[ffMathy]

@ajafff your solution also produces an unexpected result when emitted.

{ [key: number]: number; } as a string turned into a TypeNode and then emitted turns into the code { [: number]: number; } .

Note how the "key" name is lost. How come? Any way to get around this?

[ajafff]

When emitting a transformed file, you always need to pass the original SourceFile object. This is then used to look up the content of not modified nodes.
In your case you probably try to combine nodes from different SourceFiles. That will always go wrong.
You need to transform that AST subtree from the other SourceFile to create synthesized nodes (ts.createXXX) from at least all literals and identifiers.

[mhegazy]

Seems related to #9883

[typescript-bot]

Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.