noswitchesbitches.js

// Before switch
 _.each(conditions.conditions, function (condition) {
	field = this.lastRecord[condition.field];
	var isVisible = false; 
	
	switch(condition.operator) {
		case "+":
			isVisible = (x == y);
			break;
		case "!=":
			isVisisble = (x !== y);
			break
		// Lots more
		// of this
		// monkey
		// business
	}
}, this);

// After switch
 _.each(conditions.conditions, function (condition) {
	field = this.lastRecord[condition.field];
	isVisible = operators[condition.operator](field, condition.value);
}, this);

// Operators.js
// A separate reusable file of operators that's nicer looking IMHO
define({
    '=': function(x, y) {
        return x == y;
    },
    '!=': function(x, y) {
        return x !== y;
    },
    '>': function(x, y) {
        return +x > +y;
    },
    '<': function(x, y) {
        return +x < +y;
    },
    'defined': function(x) {
        return x;
    },
    'undefined': function(x) {
        return !x;
    }
});