JavaScript中两组功能如何切换

Question

I want to make parts of a Cypress test suite run a set of functions based on a configuration variable. Ie version 1 of the function showMessage should be used if the version variable is 1, and version 2 if the version variable is 2. I can do it with if statements like demonstrated below. I am a JavaScript noob, but I know there are more elegant ways of doing it.

function showMessage(version) {
    if (version == '1') {
        console.log('Version 1');
    }
    else {
        console.log('Version 2')
    }
}

showMessage('2');

I would ideally like to have the functions in separate folders, each defining their own version of showMessage (without the if statement), but I am not sure how to do it properly in JavaScript.

In a way, I'm asking for an extremely lightweight dependency injection mechanism.

Answer 1

There is many many ways to do that. It is basically a decision of what is less work and is the most readable. But at the end there is never a way around for selecting what you want. A different approach to if in each function would be:

 var a = {}; var b = {}; a.showMessage = () => { console.log('Version 1'); } b.showMessage = () => { console.log('Version 2'); } version ='1' //set up 'reference' object c in one place, based on the selected version c = (version == '1'? a: b); //Then every time we call showMessage, use the reference object (no ifs) c.showMessage();

Another option would be to use the prototype of a function. That is to be said, literally the same as the above example but with the fact that it is more reuseable in some kind of way.