Express, correct way to check the presence of a parameter in the body

Question

Which is the correct way of checking the presence of a parameter in the body?

I'm using if(req.body.hasOwnProperty('myParam')){...} but i see that someone just write if(req.body.myParam){...} but this second option will return false if the param has a numeric value of 0, doesn't it?

Answer 1

Right.

if you want to check if the attribute exists so hasOwnProperty will do the job.

Using req.body.myParam will return false for any falsely such as 0, '', false, null or undefined.

Also note that the dot notation and the hasOwnProperty method do no have the same behavior :

The hasOwnProperty() method returns a boolean indicating whether the object has the specified property as its own property (as opposed to inheriting it).

So it can be confusing, for example, run the above snippet :

var o = new Object();

if (o.toString) {
  console.log('Dot notation can be confusing, inherited property example : ', o.__proto__.toString);
}

if (o.hasOwnProperty('toString')) {
  // nope
} else {
  console.log("that's why the hasOwnProperty method can be preferred");
}