1 files changed, 35 insertions, 0 deletions
diff --git a/plugins/CoreHome/vue/src/getFormattedEvolution.ts b/plugins/CoreHome/vue/src/getFormattedEvolution.ts
new file mode 100644
index 0000000000..40aa032e9e
--- /dev/null
+++ b/plugins/CoreHome/vue/src/getFormattedEvolution.ts
@@ -0,0 +1,35 @@
+/*!
+ * Matomo - free/libre analytics platform
+ *
+ * @link https://matomo.org
+ * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
+ */
+
+function calculateEvolution(currentValue: string|number, pastValue: string|number) {
+  const pastValueParsed = parseInt(pastValue as string, 10);
+  const currentValueParsed = parseInt(currentValue as string, 10) - pastValueParsed;
+
+  let evolution: number;
+
+  if (currentValueParsed === 0 || Number.isNaN(currentValueParsed)) {
+    evolution = 0;
+  } else if (pastValueParsed === 0 || Number.isNaN(pastValueParsed)) {
+    evolution = 100;
+  } else {
+    evolution = (currentValueParsed / pastValueParsed) * 100;
+  }
+
+  return evolution;
+}
+
+function formatEvolution(evolution: number) {
+  return `${evolution > 0 ? '+' : ''}${Math.round(evolution)}}%`;
+}
+
+export default function getFormattedEvolution(
+  currentValue: string|number,
+  pastValue: string|number,
+): string {
+  const evolution = calculateEvolution(currentValue, pastValue);
+  return formatEvolution(evolution);
+}