How to write if to judge multiple conditions in js

Methods to evaluate multiple conditions in JavaScript include using the || (or) operator, && (and) operator, nested if statements, and switch statements (only applicable to comparing one value).

How to use If in JavaScript to determine multiple conditions

Use if in JavaScript to determine the number of multiple conditions method.

1. Use the || (logical OR) operator

The || (logical OR) operator is used to determine whether any of multiple conditions is true. .

<code class="javascript">if (condition1 || condition2) {
  // 条件 1 或条件 2 为真时的代码
}</code>

2. Use the && (logical AND) operator

&& (logical AND) operator is used to determine whether multiple conditions are true.

<code class="javascript">if (condition1 && condition2) {
  // 条件 1 和条件 2 都为真时的代码
}</code>

3. Use nested if statements

Nested if statements can be used to determine multiple conditions and execute different codes based on different conditions.

<code class="javascript">if (condition1) {
  // 条件 1 为真时的代码
} else if (condition2) {
  // 条件 1 为假，条件 2 为真时的代码
} else {
  // 条件 1 和条件 2 都为假时的代码
}</code>

4. Use the switch statement (limited to comparing one value)

The switch statement can be used to compare a value with multiple options and perform different actions based on the match code.

<code class="javascript">switch (value) {
  case option1:
    // 值等于选项 1 时的代码
    break;
  case option2:
    // 值等于选项 2 时的代码
    break;
  default:
    // 值与任何选项都不匹配时的代码
}</code>

Example

The following example uses the || operator to determine whether either of two conditions is true:

<code class="javascript">const age = 18;
const isCitizen = true;

if (age >= 18 || isCitizen) {
  console.log("可以投票");
} else {
  console.log("不能投票");
}</code>

The above example uses embedding The set of if statements determines three conditions:

<code class="javascript">const score = 85;

if (score >= 90) {
  console.log("A");
} else if (score >= 80) {
  console.log("B");
} else if (score >= 70) {
  console.log("C");
} else {
  console.log("D");
}</code>

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