3 Equals Signs Javascript

3 min read Jun 22, 2024

3 Equals Signs in Javascript: Strict Equality (===)

In Javascript, the === operator, often referred to as the "strict equality" operator, is used to compare two values for strict equality. It checks if both the value and the data type of the two operands are exactly the same.

Let's break down what this means:

Value and Data Type

Value: This refers to the actual content of the variable. For instance, the value of the variable x could be the number 5 or the string "Hello".
Data Type: This specifies the type of the variable, such as a number, string, boolean, or object.

Strict Equality Comparison

The === operator ensures that both the value and data type are identical for the comparison to return true. If even one of them is different, the comparison will return false.

Here are some examples:

Example 1:

let x = 5;
let y = "5";

console.log(x === y); // Output: false

In this example, although x and y have the same value (5), their data types are different (x is a number, y is a string). Therefore, the === operator returns false.

Example 2:

let x = 5;
let y = 5;

console.log(x === y); // Output: true

Here, both x and y have the same value (5) and the same data type (number). Consequently, the === operator returns true.

Why Use Strict Equality?

The === operator offers a more precise and reliable comparison than the loose equality operator (==). Loose equality can perform type coercion, converting one operand to match the type of the other, potentially leading to unexpected behavior.

For example, 0 == "" returns true because "" is coerced to 0. However, 0 === "" returns false because they have different data types.

Using strict equality avoids these unexpected outcomes and ensures clear and consistent comparisons.

Summary

In essence, the === operator is a powerful tool in Javascript for accurate and reliable comparisons. By checking both the value and the data type, it eliminates the potential for ambiguity and unintended type coercion.