The operators === and !== are the strict comparison operators. This means that if the operands have different types, they are not the same. For example,

 1 === "1" // false 1 !== "1" // true null === undefined // false

The == and != operators are the relaxed comparison operators. That is, if the operands have different types, JavaScript tries to convert them so that they are comparable. For example

 1 == "1" // true 1 != "1" // false null == undefined // true