> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hasmcp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# How can I use JavaScript to calculate totals or format dates within an API response?

> Performing payload manipulation that declarative matchers like JMESPath cannot structurally achieve.

# Calculating Totals & Formatting Dates

When connecting legacy or unoptimized API platforms to your AI Agents, you will frequently encounter datasets requiring mathematical computation or strict cryptographic formatting.

Because LLMs inherently struggle to consistently execute deep variable math in a single prompt natively, you can explicitly offload this deterministic state processing to the HasMCP Goja backend explicitly.

### Example: Calculating Inventory

```javascript theme={null}
var warehouse_total_value = 0;
 
// Calculate total price of all items effectively
input.inventory.forEach(function(item) {
  warehouse_total_value += (item.qty * item.price_per_unit);
});
 
// Return the final evaluated object directly
return {
  global_inventory_valuation: warehouse_total_value
};
```

### Example: Standardizing Unix Timestamps

The following example parses an archaic API returning `1694200000` and normalizes the payload to strictly readable ISO8601 strings seamlessly:

```javascript theme={null}
// Iterate the events recursively 
for (var i = 0; i < input.length; i++) {
  var rawUnix = input[i].server_startup_time;
 
  // JS evaluates unix timestamps in milliseconds 
  input[i].server_startup_time = new Date(rawUnix * 1000).toISOString();
}
 
return input;
```

This transforms raw bytes into `2023-09-08T19:06:40.000Z`, providing the LLM agent flawless temporal reasoning proactively and securely.