JavaScript-Not able to Implement multiple Or in an IF statement

I am a JavaScript newbie trying to Implement an If statement with multiple "OR" conditions

I have no Issues comparing two Items, but when I do three, like this

if(dealStage=="Stage1" ||dealStage=="Stage2"||dealStage=="Stage3"){}

The condition doesn't get satisfied even when the Deal Stage is set to Stage3.

Not sure what I am doing wrong.

Any help on this matter would be greatly appreciated.