Diferencias

Muestra las diferencias entre dos versiones de la página.

--- wiki2:js [2022/11/03 15:17]
alfred [Default arguments on functions]
+++ wiki2:js [2022/11/03 16:21] (actual)
@@ Línea 1115: / Línea 1115: @@
 <code javascript>
 const lordify = firstName => `${firstName} of Canterbury`;
+</code>
+Arrow functions protect the scope of this.
+For example this fails:
+<code javascript>
+const tahoe = {
+  mountains: ["Freel", "Rose", "Tallac", "Rubicon", "Silver"],
+  print: function(delay = 1000) {
+    console.log(this); // Window {}
+    setTimeout(function() {
+      console.log(this.mountains.join(", "));
+    }, delay);
+}};
+tahoe.print(); // Uncaught TypeError: Cannot read property 'join' of undefined
+</code>
+But this not:
+<code javascript>
+const tahoe = {
+	mountains: ["Freel", "Rose", "Tallac", "Rubicon", "Silver"],
+	print: function(delay = 1000) {
+		setTimeout(() => {
+			console.log(this.mountains.join(", "));
+		}, delay);
+	}
+};
+tahoe.print(); // Freel, Rose, Tallac, Rubicon, Silver
 </code>

Programming