Add an example on how to use webpack with webextensions

webpack-modules/popup/left-pad.js

@@ -0,0 +1,23 @@
+const leftPad = require("left-pad");
+
+const resultNode = document.getElementById("result");
+const textNode = document.getElementById("text");
+const amountNode = document.getElementById("amount");
+const withNode = document.getElementById("with");
+
+document.getElementById("leftpad-form").addEventListener("submit", (e) => {
+    e.preventDefault();
+
+    console.log("padding");
+    resultNode.value = leftPad(textNode.value, amountNode.valueAsNumber, withNode.value);
+}, false);
+
+document.getElementById("pad-bg").addEventListener("click", (e) => {
+    chrome.runtime.sendMessage({
+        text: textNode.value,
+        amount: amountNode.valueAsNumber,
+        with: withNode.value
+    }, (result) => {
+        resultNode.value = result;
+    });
+});