如何使用 typscript 编译器在 typescript 文件中向现有 json object 添加另一个属性？

Question

I have the following file with me

const ServerURL = '';
export const URLConfig = {
    ServerURL: ServerURL,
    entityKeyUrl: ServerURL + '/path/to/resource/',
}

Now I want to add another url to this object using ast/typescript compiler apis.

What have I tried?

I have read the source file and extracted the text from the SourceFile but now I don't know how to update it with the new text.

Here is my code (hiding the other parts of the code)

const source = getSourceFile(tree, '/path/to/serverurl.constants.ts');
const txt = source.getText();
const closingBrace = txt.lastIndexOf('};');
const aLineAboveClosingBrace = closingBrace - 2;
source.update("Hello", ts.createTextChangeRange(ts.createTextSpan(0, txt.length), "Hello".length + txt.length));

It results in an error "Debug failed, false expression". Can somebody guide me in this?

Update 1 I have been able to do some string manipulation and been able to generate my text but now to be able to create a file, I used ts.createSourceFile but that did not generate any file for me.

Answer 1

If you want to change it in compilation time, I'd suggest you use Transformation API to do that.

Currently TypeScript doesn't support to use custom transformers by using tsc , but you can use tools like ttypescript . See here to see what's the custom transformer should be like. Also, in the repo's readme you can find examples of other custom transformers (you can use one of them as your start point).

Another helpful tool you can use is ts-ast-viewer - it helps you see what the AST is and how to create the same (and then modify it) AST for the code.