v8::ScriptOrigin line/column offset

[Bit Cortex]

Hello!

Could someone describe the purpose of the line and column offset properties of v8::ScriptOrigin? What effect do nonzero values have?

Thanks!

[Ben Noordhuis]

I believe they're intended to offset IIFEs[1] and other wrappers that
embedders may want to add around the user's script code.

[https://en.wikipedia.org/wiki/Immediately-invoked_function_expression]

[Bit Cortex]

Thanks, but what's the actual effect of setting the line or column offset to a nonzero value?

Based on your description, I'd guess that it might affect stack traces and possibly debugging.

Can someone confirm that? Or do I not understand correctly?

[Ben Ernst]

Yes that's right, when a debugger or an error message says you're on line X and column Y, it deducts the values you specify in the offsets. So if you transform user's code in some form, the error messages can be adjusted to still have the right line numbers and column numbers.

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[Simon Zünd]

This is used e.g. when your script is inline in <script> tags in HTML. Then the ScriptOrigin will contain the line/column of the opening <script> tag, so stack traces contain the absolute line/column number inside the HTML document.

I don't know if the information is used in other places besides stack traces and debugging though.

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[Bit Cortex]

Thanks for your responses!