What does || mean in js

The "||" operator in JS is a logical XOR operator, used to determine whether at least one of two expressions is true. The usage is as follows: if expression1 is true, return expression1. If expression1 is false, return expression2.

The meaning of "||" operator in JS

"||" in JS is a logical OR operation operator, also known as the logical XOR operator, whose function is to determine whether at least one of two expressions is true.

Syntax

<code>expression1 || expression2</code>

Usage

• Returns # if expression1 is true ##expression1.
If
• expression1 is false, return expression2.

Example

<code>const x = true || false; // 输出: true
const y = false || true; // 输出: true
const z = false || false; // 输出: false</code>

Influencing factors

• Short circuit evaluation: The "||" operator follows the short-circuit evaluation principle, that is, if expression1 is true, expression2 will not be evaluated.
• True and false values: In JS, true and false values ​​only include true and false, any other values ​​are considered false values .

Common uses

• Set default value: Can be used to set a default value for a variable, if the variable is not defined or is If false, the alternate value is used.
• Combined expressions: can be used to combine multiple Boolean expressions, returning true when at least one expression is true.
• Conditional rendering: In frameworks such as React, it can be used to render based on conditions. If the condition is true, the first expression is rendered, otherwise the second expression is rendered.

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