How to write if to judge multiple conditions in js

The if statement that determines multiple conditions in JavaScript can be implemented through the logical operator && (and operator) or || (or operator). Among them, && requires all conditions to be true, while || requires any condition to be true. Pay attention to precedence order (&& is higher than ||) and use parentheses for grouping to ensure correct application of operators.

if statement to determine multiple conditions in JavaScript

In JavaScript, you can use the logical operator (&& and ||) to judge multiple conditions.

• && (AND operator) : If all conditions are true, the expression is true, otherwise it is false.
• || (or operator) : If any condition is true, the expression is true, otherwise it is false.

If necessary, you can use parentheses to group different conditions.

To use the && and || operators to evaluate multiple conditions, follow these steps:

1. List all conditions: First, list all Conditions that require judgment.
2. Use logical operators: Connect conditions using the && or || operators, depending on the conditions that need to be met.
3. Bracket grouping (optional): Use parentheses to group conditions as needed to ensure operators are applied correctly.

Example:

Judge the following conditions:

• The user is older than 18 years old
• The user is logged in

<code class="javascript">if (userAge > 18 && isLoggedIn) {
  // 条件满足，执行代码块
} else {
  // 条件不满足，执行其他代码块
}</code>

In this example, the && operator is used to check two conditions. The block of code that satisfies the condition will be executed only if both conditions are true. Otherwise, the code block whose condition is not met will be executed.

Note: The precedence of the

• operator is && is higher than ||.
• Always use parentheses to ensure correct operator precedence.
• Ensure that the type of the condition is consistent with the expected type of the logical operator.

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