I like the pretty form of testing indexOf with an array, but be aware, this doesn't work in all browsers (because Array.prototype.indexOf is not present in old IExplorers).
However, there is a similar way by using jQuery with the $.inArray() function :
if ($.inArray(field, ['value1', 'value2', 'value3']) > -1) {
alert('value ' + field + ' is into the list');
}
It could be better, so you should not test if indexOf exists.
Be careful with the comparison (don't use == true/false), because $.inArray returns the index of matching position where the value has been found, and if the index is 0, it would be false when it really exist into the array.