How to define boolean type in js

In JavaScript, the Boolean type is used to represent true and false values, including true and false. The method of defining Boolean variables is as follows: Assignment operator: Directly assign true or false Boolean operation: Use Boolean operators to generate Boolean values Comparison operators: Use comparison operators to generate Boolean values Conditional operators: Generate Boolean values based on conditional expressions Built-in function Boolean (): Convert other data types to Boolean values

Boolean type defined in JavaScript

In JavaScript, The Boolean type is used to represent true and false values. There are two Boolean values: true and false. You can use the following methods to define Boolean variables:

1. The assignment operator

directly assigns true or false to Just use variables:

let isLoggedIn = true; let isOffline = false;

2. Boolean operations

Boolean operators (such as &&,||,!) can produce Boolean values. Just assign the result to a variable:

let isOver18 = age >= 18; // 如果 age 大于或等于 18，则为 true let isNotEqual = username !== 'admin'; // 如果 username 不等于 'admin'，则为 true

3. Comparison operator

Comparison operator (such as ==, !=, <, >) can also produce Boolean values. Just assign the result to a variable:

let isSamePassword = password1 === password2; // 如果 password1 等于 password2，则为 true let isGreaterThanZero = balance > 0; // 如果 balance 大于 0，则为 true

4. Conditional operator

Conditional operator (? :) can be expressed based on conditions The formula generates a Boolean value. The syntax is:

variable = (condition) ? trueValue : falseValue;

let hasPermission = isLoggedIn ? 'admin' : 'guest'; // 如果 isLoggedIn 为 true，则 hasPermission 为 'admin'，否则为 'guest'

5. Built-in function

Boolean() The function can convert other data types to Boolean values:

let isTruthy = Boolean(value); // 将 value 转换为布尔值

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