file exists function help

[WingDust]

emscripten version :2.0.1
I try to write a C++ function for validate file exists.
here is my code

#ifndef EM_PORT_API
# if defined(__EMSCRIPTEN__)
#   include <emscripten.h>
#   if defined(__cplusplus)
#       define EM_PORT_API(rettype) extern "C" rettype EMSCRIPTEN_KEEPALIVE
#   else
#       define EM_PORT_API(rettype) EMSCRIPTEN_KEEPALIVE
#   endif
# else
#   if defined(__cplusplus)
#       define EM_PORT_API(rettype) extern "C" rettype
#   else 
#       define EM_PORT_API(rettype) rettype
#   endif
# endif
#endif

#ifdef _WIN64
#include <io.h>
#else
#include <unistd.h>
#endif

EM_PORT_API(int) exists(const char *pathname)
{
#ifdef _WIN64
  return _access(pathname,0);
#else
  return access(pathname,F_OK);
#endif
}

Actually I write for run in Electron
but I don't how to use it after I compiled it get a.out.js a.out.wasm
Mostly I saw the example is for web or use node test.js
can help me ?
or this function can achieve another way

[curiousdannii]

You probably should look at these pages of the docs, which will let you create a JS function which you can call from your C code. That JS function can then use the Node API to check if the file exists.

https://emscripten.org/docs/porting/connecting_cpp_and_javascript/Interacting-with-code.html#calling-javascript-from-c-c

[WingDust]

@curiousdannii
I rewrite C++ code

#include "/usr/lib/emscripten/system/include/emscripten.h"
#include <string>
using namespace std;

#ifndef EM_PORT_API
# if defined(__EMSCRIPTEN__)
#   include <emscripten.h>
#   if defined(__cplusplus)
#       define EM_PORT_API(rettype) extern "C" rettype EMSCRIPTEN_KEEPALIVE
#   else
#       define EM_PORT_API(rettype) EMSCRIPTEN_KEEPALIVE
#   endif
# else
#   if defined(__cplusplus)
#       define EM_PORT_API(rettype) extern "C" rettype
#   else 
#       define EM_PORT_API(rettype) rettype
#   endif
# endif
#endif



//EMSCRIPTEN_KEEPALIVE void hi(const char* p){
  EM_PORT_API(int) hi(const char* p){
  // string a = "function show(arg){console.log(arg);};";
     string b = p;
    // string c = "show(\"";
    // string d = "\");";
    //
    string test = "const fs = require('fs');";
    string a = "function show(arg){let check = fs.existsSync(arg";
    string d = ");if(check){return 1}else{return 0};};show(\"";
    string e = "\");";

    // string run = a+c+p+d;
    string run = test+a+d+b+e;
    int num = emscripten_run_script_int(run.c_str());
    return num;
}

compile em++ run.cpp -s "EXTRA_EXPORTED_RUNTIME_METHODS=['ccall','cwrap']" -o run.js

and do test for node is correct
test.js:
run node test.js

var em_module = require('./run.js');
em_module['onRuntimeInitialized'] = onRuntimeInitialized;

//console.log(em_module.run());
//em_module._hi('qweqwe');

function onRuntimeInitialized(){
    var s = '/home/wingdust/Programming/Emcc/for.txt';
    let a = em_module.ccall('hi','number',['string'],[s])
    console.log(a)
  
}

But I want use it for electron+typescript+vite ,problem show up
And I still try write run.d.ts for typescript according #10271
run.d.ts:

/// <reference types="emscripten"/>
interface em_moduel extends EmscriptenModule {
    ccall:typeof ccall;
    hi(arg:string):number;
}

And In Electron code
typescript:

/// <reference types="emscripten"/>
 let em_moudle = require("../cplusplus/run.js")
em_moudle['onRuntimeInitialized'] = onRuntimeInitialized

function  onRuntimeInitialized() {
  let a = '../assets/electron.png'
  let b = em_moudle.ccall('hi','number',['string'],[a])
  console.log(b);
}

let em_moudle = require("../cplusplus/run.js") it's error

It' has any experience to how to use wasm file for Electron

[stale]

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