generalized .length check on functions

Question

When i write a function in JS or jQuery and a parameter is required, i use the if something.length trick...

this.example = function(e) {
  if ($(e).length) {
    /*blablabla*/
  } else {
    return false;
  }
}

But i dont want to do this in all functions. Is there a way to generalize this?

like:

this.ck = function(e) {
  return function(e){
    if (!(e.length)) { return false;}
  }
}

this.example = function(e) {
     ck(e)
    /*blablabla*/

}

Answer 1

Maybe this, but see below:

function ifNonEmpty(f) {
  return function(e) {
    if (!$(e).length) return false;
    return f(e);
  };
}

You'd use that like this:

var myCoolFunction = ifNonEmpty(function myCoolFunction(e) {
  // your implementation
};

I would however suggest that instead of writing functions that take jQuery objects as parameters, you write those functions as your very own jQuery plugins.

Answer 2

I would suggest the following.

This example would first test whether the parameter actually contains anything (i.e. is not null), then your .length check could be on whether it

function isNonEmpty(p){
    if ( (p != null) && (p.length > 0) ){
        //test
    }
}

I would be wary of using .length, anyway. For example, if you pass a string .length will have a value!

To test if something is a jQuery object:

alert(p instanceof jQuery); //will alert "true" if p is a jQuery object.

So, this gives us:

function isNonEmpty(p){
    if ( (p != null) && (p instanceof jQuery) && (p.length > 0) ){
        //test
    }
}

Or something of that ilk. Either way, there should be sufficient code there to tailor to your intent.