Added 'supply' page to create negative register transactions, updated translation

static/css/supply.css

@@ -0,0 +1,6 @@
+form {
+    width: 24rem;
+}
+#supplyPrice {
+    width: 10rem;
+}

static/js/supply.js

@@ -0,0 +1,56 @@
+document.addEventListener("DOMContentLoaded", () => {
+
+    // elements
+
+    let supply_description = document.getElementById("supplyDescription");
+    let supply_price = document.getElementById("supplyPrice");
+
+    let supply_form = document.getElementById("supplyForm");
+    let status_info = document.getElementById("statusInfo");
+    let supply_submit_button = document.getElementById("supplySubmitBtn");
+
+    // custom submit method
+
+    supply_form.addEventListener("submit", (event) => {
+
+        supply_submit_button.disabled = true;
+
+        event.preventDefault(); // Don't do the default submit action!
+
+        if (isNaN(parseFloat(supply_price.value)) || supply_description.value == "") {
+            status_info.innerText = "Please enter a description and price."
+            supply_submit_button.disabled = false;
+        }
+
+        let xhr = new XMLHttpRequest();
+        let formData = new FormData(supply_form);
+
+        xhr.addEventListener("load", (event) => {
+
+            status_ = event.target.status;
+            response_ = event.target.responseText;
+
+            if (status_ == 200 && response_ == "success") {
+                status_info.innerText = "Success.";
+                window.location.replace("/");
+            }
+            else {
+                status_info.classList.add("errorText");
+                status_info.innerText = "An error occured.";
+                window.setTimeout(() => { window.location.reload() }, 5000);
+            }
+
+        })
+
+        xhr.addEventListener("error", (event) => {
+            status_info.classList.add("errorText");
+            status_info.innerText = "An error occured.";
+            window.setTimeout(() => { window.location.reload() }, 5000);
+        })
+
+        xhr.open("POST", "/api/supply");
+        xhr.send(formData);
+
+    });
+
+})