QuickJS hello world, without qjs

[anuragvohraec]

Hi All,

I am new to quickjs.
I just wanted to use core JS-engine, without qjs or qjsc.

So I wrote up this hello world code in CPP (based on CMAKE, and linking the .o files of quickjs in the code).

#include <iostream>
#include "./lib/quickjs/quickjs.h"

# define MY_APP_VERSION 4

static void printFunction(const char* s){
    std::cout<<s<<std::endl;
}

JSValue js_print_func(JSContext *ctx, JSValueConst this_val, int argc, JSValueConst *argv){
    const char* s = JS_ToCString(ctx,argv[0]);
    printFunction(s);
    return JS_UNDEFINED;
}

int main(int argc, char** argv) {
    std::cout << "MyApp, version: " << MY_APP_VERSION <<std::endl;

    JSRuntime *rt=JS_NewRuntime();
    if(rt == NULL){
        std::cout << "Problem while getting JS runtime" << std::endl;
        return 1;
    }
    JSContext *ctx=JS_NewContext(rt);
    if (ctx == NULL) {
        JS_FreeRuntime(rt);
        std::cout << "Problem while getting JS context" << std::endl;
        return 1;
    }

    //Attaching a print1 prop to global object
    auto global_obj = JS_GetGlobalObject(ctx);
    JS_SetPropertyStr(ctx, global_obj, "print1",
                     JS_NewCFunction(ctx, js_print_func,"print1",1));


    //evaluating script
    const char* script = "print1('hello world');";
    auto val = JS_Eval(ctx,script, sizeof(script), "<evalScript>",JS_EVAL_TYPE_GLOBAL);

    if (JS_IsException(val)) {
        auto error = JS_GetException(ctx);
        std::cout<<JS_ToCString(ctx,error)<<std::endl;
    }

    std::cout << "MyApp stopped"<< std::endl;
}

I am not able to figure out what I am doing wrong , the eval always output :

MyApp, version: 4
SyntaxError: unexpected end of string
MyApp stopped

I have searched entire internet, which shows basic hello world example to get started.
Please can some one help me on this regards, how to correct this code.

[chqrlie]

Hello Anurag, I see two problems in you code: - js_print_func() should be defined as a C function, inside an extern “C” { } block, but I don’t think this is causing the problem. - in JS_Eval(ctx,script, sizeof(script), "<evalScript>",JS_EVAL_TYPE_GLOBAL); you pass sizeof(script), which is the size of a pointer, not the length of the string. You should instead pass strlen(script). Best Chqrlie.

…

On 13 Oct 2022, at 16:25, Anurag Vohra ***@***.***> wrote: Hi All, I am new to quickjs. I just wanted to use core JS-engine, without qjs or qjsc. So I wrote up this hello world code in CPP (based on CMAKE, and linking the .o files of quickjs in the code). #include <iostream> #include "./lib/quickjs/quickjs.h" # define MY_APP_VERSION 4 static void printFunction(const char* s){ std::cout<<s<<std::endl; } JSValue js_print_func(JSContext *ctx, JSValueConst this_val, int argc, JSValueConst *argv){ const char* s = JS_ToCString(ctx,argv[0]); printFunction(s); return JS_UNDEFINED; } int main(int argc, char** argv) { std::cout << "MyApp, version: " << MY_APP_VERSION <<std::endl; JSRuntime *rt=JS_NewRuntime(); if(rt == NULL){ std::cout << "Problem while getting JS runtime" << std::endl; return 1; } JSContext *ctx=JS_NewContext(rt); if (ctx == NULL) { JS_FreeRuntime(rt); std::cout << "Problem while getting JS context" << std::endl; return 1; } //Attaching a print1 prop to global object auto global_obj = JS_GetGlobalObject(ctx); JS_SetPropertyStr(ctx, global_obj, "print1", JS_NewCFunction(ctx, js_print_func,"print1",1)); //evaluating script const char* script = "print1('hello world');"; auto val = JS_Eval(ctx,script, sizeof(script), "<evalScript>",JS_EVAL_TYPE_GLOBAL); if (JS_IsException(val)) { auto error = JS_GetException(ctx); std::cout<<JS_ToCString(ctx,error)<<std::endl; } std::cout << "MyApp stopped"<< std::endl; } I am not able to figure out what I am doing wrong , the eval always output : MyApp, version: 4 SyntaxError: unexpected end of string MyApp stopped I have searched entire internet, which shows basic hello world example to get started. Please can some one help me on this regards, how to correct this code. — Reply to this email directly, view it on GitHub <#135>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AE5F5KUS3OXO6EXNFRQ5BMTWDALXBANCNFSM6AAAAAAREKZYVQ>. You are receiving this because you are subscribed to this thread.

[anuragvohraec]

you pass sizeof(script), which is the size of a pointer, not the length of the string. You should instead pass strlen(script). Best Chqrlie.

I am feeling silly. Thank you.