Shopify add cart properties. How do this properties work? It disappears after page refresh - shopify

Question

I am setting properties when adding to cart.
Ex:
var formdata=[
"items":{
id:123456,
quantity:1
properties:{'flag':true}
}
];
added using api : /cart/add.js
Details I get from cart.js without refresh
response from : /cart/add.js and cart.js
[
{
"id": 32423423423423,
"properties": {
"flag": true
},
"quantity": 1,
"variant_id": 42705234345345,
}
]
The above items get added successfully to cart. After adding I again fetch the cart details and It has this properties value.But when I refresh the page cart items properties does not have any value.
Ex Currently I am getting this only when page is refreshed:
response from cart.js after page refresh
properties:{
Ref: 0
}
What this properties is?
Why is this happening? If worked, will this properties be available on order create webhook? It only disappears when refreshed. Moreover main reason to add this properties is to receive this properties in order-create webhook to distinguish from normal order. If anyone having other alternative please suggest.

Answer 1

Adding a product to the cart like so:
fetch('/cart/add.js', {
method: "post",
headers: {
"content-type": "application/json"
},
body: JSON.stringify({
items: [
{
quantity: 1,
id: 33116507373620,
properties: {
'flag': true
}
}
]
})
})
And getting the cart.js like so:
fetch('/cart/add.js').then(res => res.json()).then(res => console.log(res))
Will get you result like so:
{
...
"items": [
{
"id": 33116507373620,
"properties": {
"flag": true
},
"quantity": 1,
...
}
],
...
}
From there on what you are doing to not get this result I'm not sure, since this is working/tested and there is no issue.
Please double check if you are targeting the correct object once you get the cart.js response. (there is no properties direct object, it's under items[0].properties in this case)