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How devtools map minified JS code back to your TypeScript source code

105 points

by manojvivek

2 days ago

| past

| 4 comments

| polarsignals.com

| HN

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zb3

2 days ago

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Tangentially related, but last year I've made a tool to recover original sources from web apps which expose source maps (with the sourcesContent value present), including enumerating all lazily loaded chunks:

https://github.com/zb3/getfrontend

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pseufaux

1 day ago

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Recent related post where Apple seemingly forgot to disable source maps for the App Store

Apple's App Store Full Front End Source Code

https://news.ycombinator.com/item?id=45804664

edit: formatting

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kayson

2 days ago

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I love it when things are displayed so nicely on mobile. This could've been a pain to read and get through but it was actually quite pleasant.

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tantalor

2 days ago

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> Notice how the decoded values give relative positions, each value represents the difference from the previous position, not absolute coordinates. This is crucial: instead of encoding large column numbers like 27698 in minified files, source maps only store small deltas like +7 or +15, making the encoded strings much more compact.

Wouldn't "offset" be a more apt term?

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manojvivek

2 days ago

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To me, “offset” sounds more like the distance from the start, whereas here the values are relative to the previous segment. Not a native english speaker, so I could be wrong.

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tantalor

2 days ago

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Offset is difference from a starting point or a previous position

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jagged-chisel

2 days ago

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“Offset” is not enough on its own. Offset from what? Start of file? Absolute offset. Previous offset? Relative offset.

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willrshansen

2 days ago

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2nd order offset. The offset from the <offset from the start of the file>

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eat_veggies

2 days ago

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perhaps the delta between offsets

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jagged-chisel

8 hours ago

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We’re gonna need the delta of deltas

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hanikesn

2 days ago

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Delta Encoding is the common term

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tracker1

2 days ago

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Agreed... Delta Encoding, or even Delta Offset would work together.

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accrual

2 days ago

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In this case I feel it's like six of one and a half-dozen of the other.

Delta definition 4: (mathematics, physics, engineering) The symbol Δ; A change in a quantity, likely from "d" for "difference"

Offset definition 7: The distance by which one thing is out of alignment with another.

Got these from Wiktionary:

* https://en.wiktionary.org/wiki/delta

* https://en.wiktionary.org/wiki/offset

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recursive

2 days ago

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It sounds equally apt to my ear. I've used both words for this concept in the past.

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paulddraper

2 days ago

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Delta and offset mean the same thing — the difference between two amounts.

Delta is perhaps slightly more obscure outside of a math setting. Perhaps.

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saghm

2 days ago

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I feel like choosing the synonym that happens to be one letter shorter when the operation is literally intended to track things in a way that's more conscise is about as "apt" as it could be!