What do three equal signs mean in js

Three equal signs (===) in JavaScript represent the strict equality operator, which checks whether two values ​​are equal, taking into account the data type. Specific meanings include: value equality: checks whether the original values ​​of two values ​​are equal, regardless of data type; data type equality: unlike the loose equality operator, the strict equality operator checks whether the values ​​belong to the same data type; NaN Special case: NaN Not equal to any other value, including itself.

The meaning of three equal signs (===) in JavaScript

In JavaScript, three equal signs (===) represents the strict equality operator. It checks if two values ​​are equal and also considers their data type. Here are some important aspects:

1. Value Equality

The strict equality operator checks whether the original values ​​of two values ​​are equal. It does not take into account the data type, so the following comparison is true:

<code>"1" === 1 // 真</code>

However, if the two values ​​have different data types, the comparison is false:

<code>1 === "1" // 假</code>

2. Data Types Equality

Unlike the loose equality operator (==), the strict equality operator also checks the data types of the two values. If the data types are different, the comparison is false:

<code>1 === "1" // 假
true === 1 // 假</code>

3. NaN special case

In JavaScript, NaN (not a number) is a special value that is the same as Any other value is not equal, including itself:

<code>NaN === NaN // 假</code>

Usage scenarios

The strict equality operator is usually used in scenarios where exact equality comparisons are required, such as:

• Check whether two variables point to the same object
• Ensure that the value is not implicitly type converted
• Perform strict comparisons in conditional statements

By using the strict equality operator, JavaScript developers can ensure that their comparisons are accurate and reliable.

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