What is the JavaScript convention for no operation?

Question

What is the JavaScript convention for no operation? Like a Python pass command.

• One option is simply an empty function: function() {}

Answer 1

I think jQuery noop() is mostly intended to prevent code from crashing by providing a default function when the requested one is not available. For example, considering the following code sample, $.noop is chosen if fakeFunction is not defined, preventing the next call to fn from crashing:

var fn = fakeFunction || $.noop;
fn() // no crash

Then, noop() allows to save memory by avoiding to write the same empty function multiple times everywhere in your code. By the way, $.noop is a bit shorter than function(){} (6 bytes saved per token). So, there is no relationship between your code and the empty function pattern. Use null, false or 0 if you like, in your case there will be no side effect. Furthermore, it's worth noting that this code...

true/false ? alert('boo') : function(){};

... is completely useless since you'll never call the function, and this one...

true/false ? alert('boo') : $.noop();

... is even more useless since you call an empty function, which is exactly the same as...

true/false ? alert('boo') : undefined;

Let's replace the ternary expression with an if statement to see how much it's useless:

if (true/false) {
    alert('boo');
} else {
    $.noop(); // returns undefined which goes nowhere
}

You could simply write:

if (true/false) alert('boo');

Or even shorter:

true/false && alert('boo');

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To finally answer your question, I guess a "conventional no operation" is the one which is never written.