Hi!
Lets say you have your own JS function called foo(x).
You implement this function in C.
JSValue js_foo(JSContext *ctx, JSValueConst this_val,
int argc, JSValueConst *argv)
parameter 'x' from JS will be argv[0] and of type JSValue
Checkout the struct JSValue in the QJS sources ....
JSValue can be of type Bool, Number, Object, Array, etc.
To work with the value of x you want to convert argv[0] from JSValue
to 'normal' C data types. I give some hints how to do this below:
Converting Strings use JS_ToCString(), for Numbers use JS_ToInt32()
Converting an object / map can be done like this
I make the blunt assumption that values (jsVal) are all of type string
JSValue jsLen = JS_GetArrayLength(ctx, jsArray); // from
quickjs.c
int arrayLen;
JS_ToInt32(ctx, &arrayLen, jsLen);
JS_FreeValue(ctx, jsLen);
// read out the array of string key - value pairs
int i = 0;
while (i + 1 < arrayLen) {
JSValue jsKey = JS_GetPropertyUint32(ctx, jsArray, i++);
JSValue jsVal = JS_GetPropertyUint32(ctx, jsArray, i++);
if (JS_IsString(jsKey) && JS_IsString(jsVal)) {
const char *keyS = JS_ToCString(ctx, jsKey);
const char *valS = JS_ToCString(ctx, jsVal);
// do something with the data
JS_FreeCString(ctx, keyS);
JS_FreeCString(ctx, valS);
}
JS_FreeValue(ctx, jsKey);
JS_FreeValue(ctx, jsVal);
}
Converting an Array works similar:
JSValue jsArrayLen = JS_GetArrayLength(ctx, jsDataArray)
int arrayLen;
JS_ToInt32(ctx, &arrayLen, jsArrayLen);
JS_FreeValue(ctx, jsArrayLen);
for (int i = 0; i < arrayLen; i++) {
// the i-th element in the data array
JSValue jsArrayElement = JS_GetPropertyUint32(ctx, jsDataArray, i);
// convert jsArrayElement to C data structure and use it
JS_FreeValue(ctx, jsArrayElement);
}
JS_FreeValue(ctx, jsDataArray);
Hope this helps (a little bit).
When I started, I had very similar questions as you asked. Unfortunately, QJS
documentation could not help me.
I found reading quickjs-libc.c sources educational
- Guido
-----Original Message-----
From: quickjs-devel-bounce@xxxxxxxxxxxxx
[mailto:quickjs-devel-bounce@xxxxxxxxxxxxx] On Behalf Of Vladimir Timofeev
Sent: 03 January 2020 13:20
To: quickjs-devel@xxxxxxxxxxxxx
Subject: [quickjs-devel] Re: How to iterate an object in c++ code?
Hi!
Did you try to use JS_GetOwnPropertyNames?
On Fri, Jan 3, 2020 at 12:16 PM sineysan <sineysan@xxxxxxx> wrote:
Thanks reply.
I pass a JS object from js to c, how I iterate all keys from the object in c
side?
I have tried to call JS_GetIterator(ctx, val), "val" is the object passed
from script, but got an error "value is not iterable".
At 2020-01-03 16:46:20, "Guido Grassel" <guido.grassel@xxxxxxxxxx> wrote:
Hi!
If this is a string that is JSON encoded, you first need to decode the string
to get JS objects (JSValue) that you can then read / write from C.
Use JS_ParseJson(..)
If you already have JS objects, you need to check their type first (functions
JS_IsNumber/String,/Object/Array), then read out (convert to C types) number,
string, bool, Array, and Object separately.
To my knowledge there is no function that would do all of this in one go.
- Guido
From: quickjs-devel-bounce@xxxxxxxxxxxxx
[mailto:quickjs-devel-bounce@xxxxxxxxxxxxx] On Behalf Of sineysan
Sent: 03 January 2020 08:34
To: quickjs-devel@xxxxxxxxxxxxx
Subject: [quickjs-devel] How to iterate an object in c++ code?
Hello:
I want to iterate a Json object in c++ code, how to do this? I can't find any
API for this purpose.
