feat: Create the calculateAbilityCost() helper

index.html

@@ -433,6 +433,7 @@
              speed: document.getElementById("inp-pool-edge-speed"),
              intellect: document.getElementById("inp-pool-edge-intellect"),
          };
+         const inpAbilityCost = document.getElementById("inp-ability-cost");
          const inpAbilityEffort = document.getElementById("inp-ability-effort");
 
          const dspAbilityPool = document.getElementById("dsp-ability-pool");
@@ -665,6 +666,19 @@
              }
          };
 
+         const calculateAbilityCost = () => {
+             var currentPool = getSelectedPool();
+
+             if (currentPool === null) return null;
+
+             var cost = Number(inpAbilityCost.value);
+             var effort = Number(inpAbilityEffort.value);
+             var effortCost = (effort) ? 3 + (effort - 1) * 2 : 0;
+             var poolEdge = Number(inpPoolEdge[currentPool].value);
+
+             return Math.max(0, cost + effortCost - poolEdge);
+         };
+
          document.addEventListener(
              "DOMContentLoaded",
              () => {