The reason JavaScript has ==, ===, and Object.is() to compare values | Saksham Khandelwal

The reason JavaScript has ==, ===, and Object.is() to compare values

JavaScript, like many programming languages, offers multiple ways to compare values. This can be confusing for developers, especially when it comes to determining the differences between the “==” operator, the “===” operator, and the Object.is() method.

These three methods each have their own unique behavior and are used in different situations. In this post, we will dive into the reasoning behind why JavaScript has multiple ways to compare values and explore when and how to use each method effectively.

We will discuss the differences in behavior and performance between the “==” operator, the “===” operator, and the Object.is() method. Understanding these tools will help you write more efficient and accurate code.

The “==” operator and the “===” operator were introduced to provide developers with different options for handling these situations. The “==” operator allows for type coercion, which can be useful when comparing values that may change their type at runtime.

On the other hand, the “===” operator does not perform type coercion, making it more strict, and can be useful for situations where the type of the operands is known and should not change.

Beside being a dynamic language, there are other reasons, why JavaScript has so many different ways to compare values.

One was it was heavily influenced by other programming languages, such as C and Java. The “==” and “===” operators were introduced to provide a similar behavior as in these languages, making it easier for developers to switch between languages.

Another reason is that the different comparison methods can make the code more readable and maintainable for other developers. For example, using “===” operator instead of “==” operator, makes it more obvious that type coercion is not intended.

Last but not least, “===” was not enough to compare certain values. Therefore Object.is() method was introduced to address some specific cases like +0 and -0, and NaN values.

Here are the use cases for using each of the comparison operators:

1. The “==” operator is known as the equality operator, which compares the values of two operands for equality. It performs type coercion meaning that it converts the operands to the same type before making the comparison. For example, if you compare a string to a number using “==”, JavaScript will convert the string to a number before making the comparison.

2. The “===” operator is known as the strict equality operator, which compares the values of two operands for equality without performing type coercion. This means that if you compare a string to a number using “===”, the comparison will return false because the two operands are of different types.

3. Finally, Object.is() method is similar to === operator but has a couple of additional behaviors. It also compares the values of two operands for equality without performing type coercion. Additionally, it can differentiate between +0 and -0, and NaN values.