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

How devtools map minified JS code back to your TypeScript source code(polarsignals.com)

107 points by manojvivek 195 days ago | 16 comments

zb3 195 days ago |

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

pseufaux 194 days ago |

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

kayson 194 days ago |

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.

tantalor 195 days ago |

> 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?

manojvivek 195 days ago | |

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.

tantalor 195 days ago | | |

Offset is difference from a starting point or a previous position

hanikesn 195 days ago | |

Delta Encoding is the common term

tracker1 194 days ago | | |

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

accrual 194 days ago | |

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

recursive 195 days ago | |

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

paulddraper 194 days ago | |

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

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

saghm 194 days ago | | |

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!