Question

I need to check if thevar[2] === ‘debug’ however thevar[2] might be undefined so if I ran the following code with it being undefined javascript would throw an error:

if (thevar[2] === 'debug') {
  console.log('yes');
}

So what I’m currently doing is:

  if (typeof thevar[2] !== 'undefined') {
    if (thevar[2] === 'debug') {
      console.log('yes');
    }
  }

Is this really the best way to do this?

Answer 1

Your first example will not throw an error. Undefined properties of objects evaluate to undefined, but they don’t throw errors.

var foo = {};
var nothing = foo.bar; // foo.bar is undefined, so "nothing" is undefined.
// no errors.

foo = [];
nothing = foo[42]; // undefined again
// still no errors

So, your second example is not needed. The first is sufficient.