javascript:void(o) problem solution sharing

The void(0) operator in JavaScript returns an undefined value, which is used to eliminate the side effects of expressions or function calls. It is mainly used in the following scenarios: 1. Eliminate expression side effects (for example: let result = 10 * (void(0)); // result is undefined); 2. Avoid function calls (for example: document.getElementById("button" ).addEventListener("click", void(0));); 3. As the default value (for example: function getDefaultValue() { return void(0); // Return undefined}).

Detailed explanation of void(0) usage in JavaScript: Practical case

##void(0) is JavaScript A special operator in , used to return undefined values. It is often used to eliminate side effects of expressions or function calls, preventing the JavaScript engine from performing unnecessary operations.

Syntax

##void(0)

The syntax is very simple: <pre class='brush:javascript;toolbar:false;'>void(0);</pre>

How to use

• Eliminate expression side effects:

  let result = 10 * (void(0)); // result 为 undefined，副作用被消除

## Avoid function calls:

• const handleClick = () => {
    // 处理点击事件代码
  };
  
  // 不调用 handleClick 函数，避免副作用
  document.getElementById("button").addEventListener("click", void(0));

As the default value:

• function getDefaultValue() {
    return void(0); // 返回 undefined
  }

Actual case

Case 1: Avoid side effects of Ajax requests

The following code uses void(0)

to avoid making unnecessary Ajax requests:

const handleAjaxRequest = () => {
  if (!condition) {
    return void(0); // 避免发送请求
  }

  // 发送 Ajax 请求
};

Case 2: Prevent the form Submit

The following code uses void(0)

to prevent the form from being submitted if the conditions are not met:

const handleFormSubmit = (e) => {
  e.preventDefault(); // 防止默认提交

  if (!validateForm()) {
    return void(0); // 阻止提交
  }

  // 提交表单
};

Notes

When using

void(0)

, please make sure to understand its behavior to avoid unnecessary performance overhead.
• void(0)
returns the
• undefined value instead of null.

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