Fix types: Comparing string not numbers to discount highest subtotal line item

User reported example does work as written/pulled into the docs, and provided a suggestion for how to fix.

See https://github.com/Shopify/shopify-dev/issues/61273 for original issue.

The example template is wrong as the end goal is to discount the highest subtotal lineitem. The example is comparing the cost of these but as strings, not numbers. It should actually be
const maxCartLine = input.cart.lines.reduce((maxLine, line) => {
if (Number(line.cost.subtotalAmount.amount) > Number(maxLine.cost.subtotalAmount.amount)) {
return line;
}
return maxLine;
}, input.cart.lines[0]);

How I interpret:

https://github.com/Shopify/discounts-reference-app/blob/09c22fb25d3a3e30ea2e68137ebfa72066823ccf/examples/javascript/default/extensions/discount-function/src/cart_lines_discounts_generate_run.js#L24-L29

User's suggestion:

  const maxCartLine = input.cart.lines.reduce((maxLine, line) => {
    if (Number(line.cost.subtotalAmount.amount) > Number(maxLine.cost.subtotalAmount.amount)) {
      return line;
    }
    return maxLine;
  }, input.cart.lines[0]);

to compare as numbers rather than strings.

Closing the original docs issue in favor of this one.

Open examples/javascript/default/extensions/discount-function/src/cart_lines_discounts_generate_run.js at the lines identified in the issue and inspect how the highest-subtotal cart line is selected. Verify that the example compares subtotal amounts numerically and that the resulting line is the one with the highest subtotal.