What do parentheses mean in js

In JavaScript, parentheses are used for function calls and grouping operations. When a function is called, parentheses surround the parameters of the function; when performing group operations, the operator within the parentheses has the highest priority.

The meaning of parentheses in JS

In JavaScript (JS), parentheses (()) have two Main uses:

1. Function call

• When calling a function, parentheses are used to enclose the parameters of the function. For example:

<code class="js">function greet(name) {
  console.log(`Hello, ${name}!`);
}

greet("John"); // 输出 "Hello, John!"</code>

2. Grouping operations

• Parents can also be used to group expressions and change the priority of operators. For example:

<code class="js">const result = (1 + 2) * 3; // 结果为 9，因为乘法优先级高于加法
const result2 = ((1 + 2) * 3); // 结果为 9，因为括号优先级最高</code>

Specific usage:

• Function call: When the function name is followed by parentheses, it means Call this function.
• Grouping operations: When the expression is enclosed in parentheses, the operations within the parentheses will be executed first.
• Parameter passing: When the function is called, the parameters are placed in parentheses.
• Priority control: Parentheses can change the priority of operators, thereby controlling the order in which expressions are evaluated.

Note:

• Empty parentheses () represent an empty function call.
• Parents can also be used for arrays and objects, but their use is different from function calls and grouping operations.

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