JS: Add way to check if view has prop

applications/system/js_app/modules/js_gui/js_gui.c

@@ -260,6 +260,26 @@ static void js_gui_view_set(struct mjs* mjs) {
     mjs_return(mjs, MJS_UNDEFINED);
 }
 
+/**
+ * @brief `View.hasProperty`
+ */
+static void js_gui_view_has_property(struct mjs* mjs) {
+    const char* name;
+    JS_FETCH_ARGS_OR_RETURN(mjs, JS_EXACTLY, JS_ARG_STR(&name));
+    JsGuiViewData* data = JS_GET_CONTEXT(mjs);
+    const JsViewDescriptor* descriptor = data->descriptor;
+
+    for(size_t i = 0; i < descriptor->prop_cnt; i++) {
+        JsViewPropDescriptor prop = descriptor->props[i];
+        if(strcmp(prop.name, name) != 0) continue;
+
+        mjs_return(mjs, mjs_mk_boolean(mjs, true));
+        return;
+    }
+
+    mjs_return(mjs, mjs_mk_boolean(mjs, false));
+}
+
 /**
  * @brief `View` destructor
  */
@@ -284,6 +304,7 @@ static mjs_val_t js_gui_make_view(struct mjs* mjs, const JsViewDescriptor* descr
     // generic view API
     mjs_val_t view_obj = mjs_mk_object(mjs);
     mjs_set(mjs, view_obj, "set", ~0, MJS_MK_FN(js_gui_view_set));
+    mjs_set(mjs, view_obj, "hasProperty", ~0, MJS_MK_FN(js_gui_view_has_property));
 
     // object data
     JsGuiViewData* data = malloc(sizeof(JsGuiViewData));

applications/system/js_app/types/gui/index.d.ts

@@ -3,7 +3,17 @@ import type { Contract } from "../event_loop";
 type Properties = { [K: string]: any };
 
 export declare class View<Props extends Properties> {
+    /**
+     * Assign value to property by name
+     * @param property Name of the property
+     * @param value Value to assign
+     */
     set<P extends keyof Props>(property: P, value: Props[P]): void;
+    /**
+     * Check if property is available
+     * @param name Name of the property
+     */
+    hasProperty(name: string): boolean;
 }
 
 export declare class ViewFactory<Props extends Properties, V extends View<Props>> {