In one of the recent JavaScript interview for a Java web development position, one of my reader was asked this questions, What is difference between comparing variables in JavaScript using "==" and "===" operator? My reader got shocked because he was from Java background and doesn't have great exposure to JavaScript, though he was pretty much familiar with some JavaScript function, event handling and some jQuery tricks, he wasn't aware of subtle details of JavaScript. He did the right think, politely said that he is not aware of difference between == and === operator. Though It did not affected his interview performance much, he was keen to know about this as soon as he finished with his interview. He asked to me as well, and that's the reason of this post. In one word, main difference between "==" and "===" operator is that former compares variable by making type correction e.g. if you compare a number with a string with numeric literal, == allows that, but === doesn't allow that, because it not only checks the value but also type of two variable, if two variables are not of same type "===" return false, while "==" return true. We will see couple of example of both operator in this article, to understand difference between them much better.
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