Iterating through JSON map in Dart - dart

Question

This may be a fundamental question but I'm trying to calculate tax from the JSON data below. However, I get this message every time I try to print the result.
Uncaught Error: TypeError: Instance of 'JsLinkedHashMap<String, Object>': type 'JsLinkedHashMap<String, Object>' is not a subtype of type 'int'
void main() {
double tax = 0.0;
int index = 0;
Map<String, dynamic> test = {
"data": {
"cartItem": [
{
"id": 30,
"productName": "Mango",
"price": 100.0,
"tax": 10.0,
"quantity": 7,
"mainImage": "http://3.109.206.91:8000/static/product_module/product/png-clipart-slice-of-mango-mango-tea-fruit-mango-game-food_HSPnZGK.png",
"totalPrice": 700.0
}
],
"grandTotal": 700.0
}
};
for(index in test['data']['cartItem']) {
tax += (test['data']['cartItem'][index]['tax'] / 100.0);
}
print(tax);
}
The reason behind running a loop is that there may be more than one object inside the data list.

Answer 1

Your code is incorrect.
void main() {
double tax = 0.0;
int index = 0;
Map<String, dynamic> test = {
"data": {
"cartItem": [
{
"id": 30,
"productName": "Mango",
"price": 10.0,
"tax": 10.0,
"quantity": 7,
"mainImage":
"http://3.109.206.91:8000/static/product_module/product/png-clipart-slice-of-mango-mango-tea-fruit-mango-game-food_HSPnZGK.png",
"totalPrice": 700.0
}
],
"grandTotal": 700.0
}
};
for (final cartItem in test['data']['cartItem']) {
tax += (cartItem['tax'] as num) / 100.0;
}
print(tax);
}