How to define boolean type in js

<blockquote><p>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</p></blockquote> <p><img src="https://img.php.cn/upload/article/202405/07/2024050718453543698.jpg" alt="How to define boolean type in js" ></p> <p><strong>Boolean type defined in JavaScript</strong></p> <p>In JavaScript, The Boolean type is used to represent true and false values. There are two Boolean values: <code>true</code> and <code>false</code>. You can use the following methods to define Boolean variables: </p> <p><strong>1. The assignment operator </strong></p> <p> directly assigns <code>true</code> or <code>false</code> to Just use variables: </p> <pre class="brush:php;toolbar:false"><code class="js">let isLoggedIn = true; let isOffline = false;</code></pre> <p><strong>2. Boolean operations</strong></p> <p>Boolean operators (such as <code>&&</code>,<code>||</code>,<code>!</code>) can produce Boolean values. Just assign the result to a variable: </p> <pre class="brush:php;toolbar:false"><code class="js">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</code></pre> <p><strong>3. Comparison operator</strong></p> <p>Comparison operator (such as <code>==</code>, <code> !=</code>, <code><</code>, <code>></code>) can also produce Boolean values. Just assign the result to a variable: </p> <pre class="brush:php;toolbar:false"><code class="js">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</code></pre> <p><strong>4. Conditional operator</strong></p> <p>Conditional operator (<code>? :</code>) can be expressed based on conditions The formula generates a Boolean value. The syntax is: </p> <pre class="brush:php;toolbar:false"><code class="js">variable = (condition) ? trueValue : falseValue;</code></pre> <pre class="brush:php;toolbar:false"><code class="js">let hasPermission = isLoggedIn ? 'admin' : 'guest'; // 如果 isLoggedIn 为 true，则 hasPermission 为 'admin'，否则为 'guest'</code></pre> <p><strong>5. Built-in function </strong></p> <p><code>Boolean()</code> The function can convert other data types to Boolean values: </p> <pre class="brush:php;toolbar:false"><code class="js">let isTruthy = Boolean(value); // 将 value 转换为布尔值</code></pre>

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