Is there an error in this Javascript code?

Question

function tipCalculator(bill) {
  var tip;
  if (bill < 50) {
    tip = 0.2 * bill;
  } else if (bill > 50 && bill < 200) {
    tip = 0.15 * bill;
  } else {
    tip = 0.10 * bill;
  }
  return tip;
}

bills = [124, 48, 268];
Tip = [tipCalculator(bills[0]),
  tipCalculator(bills[1]),
  tipCalculator(bills[2])
];

console.log(Tip);

I have written this Javascript code pls tell me if this is correct or not because I have not defined the Arrays bills and Tip

When you don't use a `var` keyword, it makes them global variables, attached to `window`. — rassar, May 16 '20 at 16:43
Given the question in title, then No! There is no error in your code. — Rush W., May 16 '20 at 16:44
Duplicate of [Is using 'var' to declare variables optional?](https://stackoverflow.com/questions/2485423/is-using-var-to-declare-variables-optional) — Guy Incognito, May 16 '20 at 16:45
@Guy Incognito - it's definitely not a duplication of that question. — Mr. Robot, May 16 '20 at 16:47
Is the code not doing what you expected it to? It's a bit unclear — ADyson, May 16 '20 at 16:56

score 3 · Answer 1 · answered May 16 '20 at 16:44

It's valid syntactically, in loose mode.

There's an argument to be made that it has an error, though, because as you say you don't declare bills or tip, so the code is relying on what I call The Horror of Implicit Globals: If you assign to an undeclared identifier in loose mode, it creates a global variable. Not a good idea.

I recommend using strict mode, which makes doing that an error:

"use strict";
function tipCalculator(bill) {
  var tip;
  if (bill < 50) {
    tip = 0.2 * bill;
  } else if (bill > 50 && bill < 200) {
    tip = 0.15 * bill;
  } else {
    tip = 0.10 * bill;
  }
  return tip;
}

bills = [124, 48, 268];
Tip = [tipCalculator(bills[0]),
  tipCalculator(bills[1]),
  tipCalculator(bills[2])
];

console.log(Tip);

Strict mode is opt-in in scripts (the "use strict"; above), but is the default within class constructs and JavaScript standard modules (aka "ESM modules").

Is there an error in this Javascript code?

1 Answers1