Understanding the '===' Operator in JavaScript

In JavaScript, the '===' operator is used to compare both the value and the type. This strict equality operator is an excellent tool for ensuring a high level of accuracy in your condition checks and providing more control over your code.

Let's consider an example:

let num = 10;
let str = '10';

console.log(num === str);  // Output: false

In this example, although the value of the variables 'num' and 'str' seem to be the same (i.e., 10), they are of different data types: 'num' is a number, and 'str' is a string. The '===' operator performs a strict check and thus returns false, since the type and value of the two operands are not equal.

On the other hand, when compared with the '==' operator, the result is 'true'. This is because the '==' operator performs type coercion and checks only for value equality, not datatype.

console.log(num == str);  // Output: true

Using '===' is considered a best practice because it eliminates the ambiguity that can come with type coercion and accidentally treating different data types as equal. By explicitly comparing data types and values, you’re ensuring a stricter check, which can help debug and avoid errors.

The '!==' operator is the negation of the '===' operator. It returns true when the value or type of the variables compared is not equal.

console.log(num !== str);   // Output: true

In summary, the '===' operator performs a strict equality check, comparing both value and type, thus offering more precision and control in comparisons. Always remember to carefully consider which type of comparison you need in your code to avoid potential bugs.