Add userscript that tries to show the tax on an item before checkout

ShowTax/showtax.js

@@ -0,0 +1,54 @@
+// ==UserScript==
+// @name         New Userscript
+// @namespace    http://tampermonkey.net/
+// @version      2024-04-12
+// @description  try to take over the world!
+// @author       You
+// @match        https://www.amazon.ca/*
+// @grant        none
+// @run-at       document-idle
+// ==/UserScript==
+
+(function() {
+    const TAX = 0.15;
+
+    // Todo: decide if it should just round up to the nearest dollar
+    // Todo: fix queryselectorall only finding one element at a time
+
+    const changeNode = function(node) {
+        var wholeNode = node.querySelector('.a-price-whole');
+        var fractionNode = node.querySelector('.a-price-fraction');
+        var whole = wholeNode ? wholeNode.textContent : '0';
+        var fraction = fractionNode ? fractionNode.textContent : '0';
+        whole = parseInt(whole);
+        fraction = parseInt(fraction);
+        whole += whole * TAX;
+        fraction += fraction * TAX;
+        whole = Math.floor(whole);
+        fraction = Math.floor(fraction);
+        if (fraction >= 100) {
+            whole += 1;
+            fraction -= 100;
+        }
+        if (fraction < 10) {
+            fraction = '0' + fraction;
+        }
+        wholeNode.textContent = whole;
+        fractionNode.textContent = fraction;
+    }
+
+    const find = function() {
+        console.log("Finding price nodes");
+        document.querySelectorAll('.a-price').forEach((node) => {
+            if (node.attributes['found']) {
+                return;
+            }
+            node.attributes['found'] = true;
+            console.log(node);
+            console.log("Price node found")
+            changeNode(node);
+        });
+    }
+    //find();
+    setInterval(find, 1000);
+})();