What is the difference between the comparison operators == and === in JavaScript?

The == operator (loose equality) performs type coercion before comparing values. The === operator (strict equality) does not perform type coercion and compares both values and data types without changes.

Examples:

// == coerces the string "5" to the number 5
console.log(5 == "5"); // true

// === does not perform type coercion, comparing the number 5 with the string "5"
console.log(5 === "5"); // false

// == considers null equal to undefined after coercion
console.log(null == undefined); // true

// === considers null not equal to undefined
console.log(null === undefined); // false

// == may convert the array [1,2] to the string "1,2" for comparison
console.log([1, 2] == "1,2"); // true

// === compares the object reference of Array [1,2] with the string "1,2"
console.log([1, 2] === "1,2"); // false

Generally, it is recommended to use === for more predictable behavior and to prevent implicit type coercion, which can lead to errors.