Clever floating point rounding in JavaScript

This is clever

+Math.PI.toFixed(0); // 3
+Math.PI.toFixed(1); // 3.1
+Math.PI.toFixed(2); // 3.14
+Math.PI.toFixed(3); // 3.142
+Math.PI.toFixed(4); // 3.1416
+Math.PI.toFixed(5); // 3.14159

toFixed(x) converts the number to a string and prefixing with the '+' converts it back to a number. Found here