JavaScript: "5" + 3 = 53?!PRO

+ joins text, - only does maths. Plus [] + [] and [] + {}.

// "5" + 3 = 53 … but "5" - 3 = 2 ?!
// + joins text when either side is a string; - only does maths.
console.log("5" + 3);          // "53" ?!
console.log("5" - 3);          // 2
console.log(Number("5") + 3);  // 8 ✓
console.log(+"5" + 3);         // 8 ✓  (unary + converts)

// Bonus traps
console.log("5" * "2");        // 10
console.log([] + []);          // "" (empty string)
console.log([] + {});          // "[object Object]"

No app yet? Install it, then open the app and type the code JS1 in Code Library.