diff --git a/d3.js/javascript/KEGG_canvas.js b/d3.js/javascript/KEGG_canvas.js
index ad0b073..1074886 100644
--- a/d3.js/javascript/KEGG_canvas.js
+++ b/d3.js/javascript/KEGG_canvas.js
@@ -304,9 +304,15 @@ var KEGG_canvas = /** @class */ (function () {
             }
         })
             .style("opacity", viz.edgeOpacity)
-            .on("mouseover", function (d) { return viz.displayTooltip(_this, d); })
-            .on("mousemove", function (d) { return viz.moveTooltip(); })
-            .on("mouseout", function (d) { return viz.removeTooltip(); })
+            .on("mouseover", function (d) {
+            viz.displayTooltip(this, d);
+        })
+            .on("mousemove", function (d) {
+            viz.moveTooltip();
+        })
+            .on("mouseout", function (d) {
+            viz.removeTooltip();
+        })
             .attr("id", "network")
             .call(this.force.drag);
         var label = node.append("text")
diff --git a/typescript/KEGG_canvas/vis.ts b/typescript/KEGG_canvas/vis.ts
index 7c2d52e..8f281a5 100644
--- a/typescript/KEGG_canvas/vis.ts
+++ b/typescript/KEGG_canvas/vis.ts
@@ -214,9 +214,15 @@ class KEGG_canvas {
                 }
             })
             .style("opacity", viz.edgeOpacity)
-            .on("mouseover", d => viz.displayTooltip(this, d))
-            .on("mousemove", d => viz.moveTooltip())
-            .on("mouseout", d => viz.removeTooltip())
+            .on("mouseover", function (d) {
+                viz.displayTooltip(this, d);
+            })
+            .on("mousemove", function (d) {
+                viz.moveTooltip();
+            })
+            .on("mouseout", function (d) {
+                viz.removeTooltip();
+            })
             .attr("id", "network")
             .call(this.force.drag)