Question

Here is my code:

function function1() {
    var ids = GetIds(); // predefined function
    if (ids.length === 0) {
        alert("Please select at least one item to procees.");
        return;
    }

    ...
}

function function2() {
    var ids = GetIds(); // predefined function
    if (ids.length === 0) {
        alert("Please select at least one item to procees.");
        return;
    }

    ...
}

function function3() {
    var ids = GetIds(); // predefined function
    if (ids.length === 0) {
        alert("Please select at least one item to procees.");
        return;
    }

    ...
}

How to extract the common part out? How to re-factor the code? The return statement is very hard to deal with. Is there any pattern relating to re-factor this code?

Thanks in advance!

    if (ids.length === 0) {
        alert("Please select at least one item to procees.");
        return;
    }

Answer 1

You can’t. The only thing you can do is moving the alert() into GetIds(). However, the function name would be a bit confusing in this case.

var ids = GetIds();
if(!ids) return;

Or you could change it like this:

GetIds(function(ids) {

});

Your GetIds function would then look e.g. like this:

function GetIds(callback) {
    var ids = ....;
    if(!ids) alert('...');
    else callback(ids);
}