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

In JavaScript, the == operator is used to perform an abstract comparison, while the === operator is used to perform a strict comparison.

An abstract comparison converts the operands to the same type before making the comparison, while a strict comparison does not perform any type conversion.

Here are a few examples to illustrate the difference between the two operators:

console.log(1 == '1'); // true
console.log(1 === '1'); // false

console.log(null == undefined); // true
console.log(null === undefined); // false

console.log(true == 1); // true
console.log(true === 1); // false

In general, it is recommended to use the strict equality operator (===) whenever possible, as it can help prevent unintended type coercion and can make your code more predictable and easier to understand. However, there may be situations where you need to use the abstract equality operator (==), such as when you are working with external libraries or APIs that expect a certain type of comparison.