In JavaScript, which operator is used to check for both value and type equality?

The operator that checks for both value and type equality in JavaScript is the strict equality operator, represented by three equal signs (===). When using this operator, JavaScript compares both the data type and the value of the operands. This means that, for the comparison to return true, the values must not only be equal but also of the same type.

For example, when comparing a number and a string using strict equality, such as 5 === '5', the result would be false because the number 5 (type number) and the string '5' (type string) are not of the same type, even though their values appear equal.

The use of strict equality helps avoid unintended type coercion that can occur with the standard equality operator (==), which converts types if necessary to check for equality. This is why using === is considered a best practice in JavaScript for more predictable and reliable comparisons.

The other options represent different concepts: the double equals operator checks for value equality but allows type coercion, a single equals sign is an assignment operator, and =! is not a valid operator in JavaScript and therefore does not serve a purpose in comparisons.