Why Does JavaScript Treat '1' 1 as a String and '1' - 1 as a Number?

JavaScript's Disparity in Handling and - Operators with Strings and Numbers

When working with JavaScript, a peculiar behavior may arise when using the and - operators on a mix of strings and numbers. Let's delve into this question to unravel the underlying logic.

Question:

Why does JavaScript treat "1" 1 as a string and "1" - 1 as a number?

Discussion:

Consider the following examples:

console.log("1" + 1); // Outputs "11"
console.log("1" - 1); // Outputs 0

The first line concatenates the string "1" with the number 1, resulting in "11." This occurs because is commonly used for string concatenation. JavaScript automatically converts the number to a string to facilitate this action.

However, in the second line, JavaScript cannot subtract a string. To resolve this, it converts the string "1" to a number, effectively resulting in 1 - 1, which equals 0.

In essence, JavaScript's behavior hinges on the nature of the operation being performed:

• Concatenation ( ): If any operand is a string, all operands are converted to strings and concatenated.
• Subtraction (-): Strings cannot be subtracted, so any string operand is converted to a number first.

The above is the detailed content of Why Does JavaScript Treat '1' 1 as a String and '1' - 1 as a Number?. For more information, please follow other related articles on the PHP Chinese website!