As others have said, this pattern is used for pattern matching when the language doesn't have specific constructs for it.

When I use it, I will extract it into a separate function, and just return the needed condition. That way you don't need to worry about case fall through.

    function getCondition(param) {
        switch (true) {
            case ConditionOne(param): return 'condition one'
            case ConditionTwo(param): return 'condition two'
            case ConditionThree(param): return 'condition three'
        }
    }