Typescript transformer, `node.parent` is undefined

Question

I'm currently using a typescript transformer api, and I found that the node.parent is undefined.

My code is:

        const transformerFactory: ts.TransformerFactory<ts.Node> = (
            context: ts.TransformationContext
        ) => {
            return (rootNode) => {
                function visit(node: ts.Node): ts.Node {
                    node = ts.visitEachChild(node, visit, context);

                    // HERE node.parent IS UNDEFINED !

                    return filterFn(node, context);


                }
        
                return ts.visitNode(rootNode, visit);
            };
        };
        
        const transformationResult = ts.transform(
            sourceFile, [transformerFactory]
        );

How can I find the parent of the node?

The root node has no parent.

tkausl
– tkausl

2021-03-12 17:09:47 +00:00
Commented Mar 12, 2021 at 17:09 — tkausl
– tkausl, Commented Mar 12, 2021 at 17:09
I don't get parent for every other node

Nexx
– Nexx

2021-03-12 17:12:37 +00:00
Commented Mar 12, 2021 at 17:12 — Nexx
– Nexx, Commented Mar 12, 2021 at 17:12

David Sherret · Accepted Answer · 2021-03-12 18:11:13Z

5

You can parse specifying to set the parent nodes:

const sourceFile = ts.createSourceFile(
    "fileName.ts",
    "class Test {}",
    ts.ScriptTarget.Latest,
    /* setParentNodes */ true, // specify this as true
);

Or do some operation on the node to get it to set its parent nodes (ex. type check the program... IIRC during binding it ensures the parent nodes are set).

Update based on comment

If you are creating these from a program, then you can do the following:

const options: ts.CompilerOptions = { allowJs: true };
const compilerHost = ts.createCompilerHost(options, /* setParentNodes */ true);
const program = ts.createProgram([this.filePath], options, compilerHost);

edited Mar 12, 2021 at 18:11

answered Mar 12, 2021 at 17:30

David Sherret

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2 Comments

Nexx Over a year ago

Is this possible if I have

this.program = ts.createProgram([this.filePath], {              allowJs: true         }); this.sourceFile = this.program.getSourceFile(this.filePath);

?

David Sherret Over a year ago

@nexis no problem!

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