4 ms·

This is a wrapper around a c++ codebase compiled with emscripten, so "pure" in the title doesn't really make sense.

danShumway 4y ago
> so "pure" in the title doesn't really make sense. I can see where you're coming from, but I've never used or heard anyone in the web world use "pure" to mean only "written entirely in Javascript without transpilation or other tools." If it hits the parts of "pure JS" that most people care about: - it's running entirely in Javascript. - it has no native dependencies. - it can run entirely clientside. - it can be embedded in a normal web page. then I think most people will be fine with using "pure" to describe it. ---- I wouldn't even have that many quibbles with their phrasing even if they were compiling to WASM. Sure, at that point it wouldn't be running as pure javascript, but it would still hit 3 of the 4 points above.
- Hasnep 4y ago
  Can emscripten compile to JS? I thought it could only compile to WASM.
  - jcelerier 4y ago
    Emscripten started as an asm.js compiler iirc ? Or even "plain" js
    - azakai 4y ago
      Yes, historically Emscripten began before asm.js, targeting pure JS. That JS backend was replaced by an asm.js backend, which was later replaced by the current wasm backend (the wasm backend in upstream LLVM). (But as already mentioned, JS is still supported today, using wasm2js.)
  - leodriesch 4y ago
    IIRC emscripten was around before Browser support for WASM was really a thing.
  - danShumway 4y ago
    I'm not sure which they're targeting, but early emscripten targeted asm.js, it predated WASM. I would consider asm.js to still be Javascript, it's just an optimized subset of the language. I'll concede though that if they're targeting WASM it's not technically pure Javascript, but it still feels a bit to me like splitting hairs since it's always been explained to me that WASM and the Javascript runtime under the hood have a lot of overlap.
  - azakai 4y ago
    Emscripten can target both WebAssembly and JavaScript. The JavaScript option uses wasm2js - it compiles first to wasm, then compiles that to JS. https://github.com/WebAssembly/binaryen#wasm2js https://github.com/WebAssembly/binaryen#wasm2js The emcc flag -sWASM=0 disables the wasm final output and emits JS instead.
- lucideer 4y ago
  From a practical standpoint, WASM is "pure JS" insofar as if I am browsing libraries and see one advertising itself as "pure JS", by convention that to me means "no FFI" or "potentially works in browser". The only place I've seen "pure JS" used in the JS world is differentiating e.g. a Postgres client implementation that does or doesn't depend on the specific version & configuration of libpq you have on your current system. That's about runtime deps, not about source language.
- pstoll 4y ago
  “Pure” does definitely connote that you’ll be able to read all the code in the given language. That’s exactly what “pure” means - “pure rust”, “pure go”, etc. IMO you can’t say the heart of all the work is a c++ lib and call it a “pure JS” anything. More accurately / correctly / usefully would be calling it “JS wrapper over a c++ library cross compiled to JS”. Or maybe “All JS at runtime” or some other qualifier. Want to see how to cross-compile a non-trivial c++ lib? Check out here! Want to see a great JS wrapper library where we had to make cross-language & cross memory-management API decisions? Check this out! But - want to read some awesome high performance image processing algorithms in JS? Not this.
  - danShumway 4y ago
    > “Pure” does definitely connote that you’ll be able to read all the code in the given language. I'm not sure where the line here is supposed to be drawn, but I don't personally think looking at asm.js code is significantly harder than looking at something like compiled Typescript, and certainly it's not any harder than looking at minified Javascript. If I'm going to be debugging code, they're both going to be annoying to look at. We're quibbling over definitions so I'm not going to say that you're wrong, "pure" can mean whatever you want it to mean. I'm just saying that most JS devs I know consider (for example) JSX code to still be pure Javascript when it's compiled. It seems a little odd to me to look at something where every single line of code is Javascript, being run entirely in a Javascript interpreter, and say that isn't actually completely real Javascript, but if the programming circles you frequent are different and think about this differently, :shrug: more power to you. > But - want to read some awesome high performance image processing algorithms in JS? Not this. I also wouldn't necessarily assume that every Open Source program written in only JS without compilation is going to be well suited for reading or learning from. But again, sort of splitting straws here -- my only concern is that you're probably going to be disappointed a lot if you equate "pure Javascript" with "readable".
  - rhacker 4y ago
    I tend to agree. When I see "pure" I don't think about the code being hand written in JS I think more about the potential of browser run OR that there are no native modules for Node required. That being said perhaps a poll is needed to find out what most people think.
- btbuildem 4y ago
  That's funny, when someone says "pure JS" I expect exactly that, something written in JS and only JS. Language matters.
  - danShumway 4y ago
    If this is compiling to asm.js then every single line of the program is Javascript and it's running entirely in a Javascript interpreter. If it's not Javascript, then what is it? I mean, if someone compiles a Markdown document and sticks the result on their website, do you say, "this isn't HTML"? People are free to use words however they want I guess, but I don't understand the perspective where the way a project was written suddenly means that the compiled result isn't Javascript -- it feels like it's taking the word "pure" in a metaphysical direction that I just don't really grok.
dang 4y ago
Ok, we've replaced "Tesseract.js – Pure JavaScript OCR" with a more specific sentence from the OP.

> so "pure" in the title doesn't really make sense. I can see where you're coming from, but I've never used or heard anyone in the web world use "pure" to mean only "written entirely in Javascript without transpilation or other tools." If it hits the parts of "pure JS" that most people care about: - it's running entirely in Javascript. - it has no native dependencies. - it can run entirely clientside. - it can be embedded in a normal web page. then I think most people will be fine with using "pure" to describe it. ---- I wouldn't even have that many quibbles with their phrasing even if they were compiling to WASM. Sure, at that point it wouldn't be running as pure javascript, but it would still hit 3 of the 4 points above.

Hasnep 4y ago
Can emscripten compile to JS? I thought it could only compile to WASM.
- jcelerier 4y ago
  Emscripten started as an asm.js compiler iirc ? Or even "plain" js
  - azakai 4y ago
    Yes, historically Emscripten began before asm.js, targeting pure JS. That JS backend was replaced by an asm.js backend, which was later replaced by the current wasm backend (the wasm backend in upstream LLVM). (But as already mentioned, JS is still supported today, using wasm2js.)
- leodriesch 4y ago
  IIRC emscripten was around before Browser support for WASM was really a thing.
- danShumway 4y ago
  I'm not sure which they're targeting, but early emscripten targeted asm.js, it predated WASM. I would consider asm.js to still be Javascript, it's just an optimized subset of the language. I'll concede though that if they're targeting WASM it's not technically pure Javascript, but it still feels a bit to me like splitting hairs since it's always been explained to me that WASM and the Javascript runtime under the hood have a lot of overlap.
- azakai 4y ago
  Emscripten can target both WebAssembly and JavaScript. The JavaScript option uses wasm2js - it compiles first to wasm, then compiles that to JS. https://github.com/WebAssembly/binaryen#wasm2js https://github.com/WebAssembly/binaryen#wasm2js The emcc flag -sWASM=0 disables the wasm final output and emits JS instead.
lucideer 4y ago
From a practical standpoint, WASM is "pure JS" insofar as if I am browsing libraries and see one advertising itself as "pure JS", by convention that to me means "no FFI" or "potentially works in browser". The only place I've seen "pure JS" used in the JS world is differentiating e.g. a Postgres client implementation that does or doesn't depend on the specific version & configuration of libpq you have on your current system. That's about runtime deps, not about source language.
pstoll 4y ago
“Pure” does definitely connote that you’ll be able to read all the code in the given language. That’s exactly what “pure” means - “pure rust”, “pure go”, etc. IMO you can’t say the heart of all the work is a c++ lib and call it a “pure JS” anything. More accurately / correctly / usefully would be calling it “JS wrapper over a c++ library cross compiled to JS”. Or maybe “All JS at runtime” or some other qualifier. Want to see how to cross-compile a non-trivial c++ lib? Check out here! Want to see a great JS wrapper library where we had to make cross-language & cross memory-management API decisions? Check this out! But - want to read some awesome high performance image processing algorithms in JS? Not this.
- danShumway 4y ago
  > “Pure” does definitely connote that you’ll be able to read all the code in the given language. I'm not sure where the line here is supposed to be drawn, but I don't personally think looking at asm.js code is significantly harder than looking at something like compiled Typescript, and certainly it's not any harder than looking at minified Javascript. If I'm going to be debugging code, they're both going to be annoying to look at. We're quibbling over definitions so I'm not going to say that you're wrong, "pure" can mean whatever you want it to mean. I'm just saying that most JS devs I know consider (for example) JSX code to still be pure Javascript when it's compiled. It seems a little odd to me to look at something where every single line of code is Javascript, being run entirely in a Javascript interpreter, and say that isn't actually completely real Javascript, but if the programming circles you frequent are different and think about this differently, :shrug: more power to you. > But - want to read some awesome high performance image processing algorithms in JS? Not this. I also wouldn't necessarily assume that every Open Source program written in only JS without compilation is going to be well suited for reading or learning from. But again, sort of splitting straws here -- my only concern is that you're probably going to be disappointed a lot if you equate "pure Javascript" with "readable".
- rhacker 4y ago
  I tend to agree. When I see "pure" I don't think about the code being hand written in JS I think more about the potential of browser run OR that there are no native modules for Node required. That being said perhaps a poll is needed to find out what most people think.
btbuildem 4y ago
That's funny, when someone says "pure JS" I expect exactly that, something written in JS and only JS. Language matters.
- danShumway 4y ago
  If this is compiling to asm.js then every single line of the program is Javascript and it's running entirely in a Javascript interpreter. If it's not Javascript, then what is it? I mean, if someone compiles a Markdown document and sticks the result on their website, do you say, "this isn't HTML"? People are free to use words however they want I guess, but I don't understand the perspective where the way a project was written suddenly means that the compiled result isn't Javascript -- it feels like it's taking the word "pure" in a metaphysical direction that I just don't really grok.

dang 4y ago

Ok, we've replaced "Tesseract.js – Pure JavaScript OCR" with a more specific sentence from the OP.