2016/10/01

How to easily avoid switch-case statement with function mapping in JavaScript

I won't advertise why it's good to avoid switch-case. While this matter might still be an open dispute I think there are usually better ways to implement what a switch-case does.

My vote would go for polymorphism, unfortunately much JavaScript code out there is not written following good OOP principles. So if you just need to work with given code base but not making a revolution there is a neat way to go:
const actions = {
    value1: actionX,
    value2: actionY,
    value3: actionZ
};

actions[value]();
Where action X, Y, Z are functions.

Of course it's good to add some check for undefined value, like:
actions[value] && actions[value]();

Or an error might be thrown if no mapping found as follows:
const action = actions[value]
        ? actions[value]
        : (value) => throw new Error('No action mapped for value: ' + value);

action(value);
Well, that's it. I believe it helps to reduce clutter in code. Just compare it to a typical switch:
switch (value) {
    case 'value1':
        actionX();
        break;
    case 'value2':
        actionY();
        break;
    case 'value3':
        actionZ();
        break;
    default: throw new Error('No action mapped for value: ' + value)
}


Exactly the same idea can be done in Groovy, Java and other languages if you are not up for polymorphism on a given case. Although for some languages with no functional paradigm, like Java before version 8, you may need to create some sort of Action class definition.

4 comments:

  1. Thank you for sharing such a nice and interesting blog with us. Hope it might be much useful for us. keep on updating...!!
    seo company in india
    digital marketing company in india
    seo company in chennai
    digital marketing company in chennai

    ReplyDelete
  2. Thank you for sharing the information here. Its much informative and really i got some valid information. You had posted the amazing article.

    Laser Root Canal Treatment In Chennai

    Best Dental Clinic In Velachery

    ReplyDelete
  3. It's interesting that many of the bloggers to helped clarify a few things for me as well as giving.Most of ideas can be nice content.The people to give them a good shake to get your point and across the command.

    Digital Marketing Company in Chennai

    ReplyDelete