Visually Optimizing JavaScript Conditional Operators that are stringed together

Question

In JavaScript let's say we have the following code

var test = 'd';
if (test != 'a' && test != 'b' && test != 'c')
  alert('were good to go');

This if seems rather lengthy to me. I would love to write something like

if (test != ('a' && 'b' && 'c')
  alert('were good to go');

Sadly this doesn't work. What is a more elegant way to write this?

Answer 1

You can't get do that, but you can get fairly close like this:

Array.prototype.contains = function(v) {
    for (var i = 0; i < this.length; i++) {
        if (this[i] == v) return true;
    }
    return false;
}

if (!['a', 'b', 'c'].contains('d')) {
    alert('good to go');
}

Most decent JS libs should contains lots of variations on list prototypes like this.

Answer 2

var test = 'd';
if (!/[abc]/.test(test))
  alert('were good to go');

Answer 3

One little helper function will take you far...

// If you write this...
function set(){
    obj={}
    for (var i=0; i<arguments.length; i++)
        obj[arguments[i]]=1;  
    return obj
}

// Then you can do this!
if (! test in set('a','b','c')){
    //Do stuff.
}

Answer 4

I concur with Matthew Crumley that this is a logically invalid question, as-is. For fun I'm going to assume you meant to use && in your question...

var test = 'd';
({a: 1, b: 1, c: 1}[ test ]) || alert("we're good to go");

or..

var test = 'd';
!(test in {a: 0, b: 0, c: 0}) && alert("we're good to go");