JavaScript prevents routing jumps

In web development, route jump is a very common operation. When the user clicks a link or submits a form, the page will jump to another page. But sometimes we want to be able to control the jump when the user clicks a link or submits a form, such as verifying the validity of the form data, or preventing data loss due to user misoperation. In this case, we need to use JavaScript to prevent routing jumps.

1. Prevent link jumps

When a user clicks on a link, the browser will jump to the corresponding page by default. But if we want to perform some processing before jumping when the user clicks the link, we need to prevent the default jump behavior. We can achieve this functionality by adding some JavaScript code in the link's onclick event.

For example, here is a link:

<a href="http://www.example.com" onclick="return false;">点击我不会跳转</a>

By adding "return false;" to the onclick event, you can prevent the link's default jump behavior.

In addition to using "return false;", you can also use the event.preventDefault() method to prevent the default jump behavior. For example:

<a href="http://www.example.com" onclick="event.preventDefault();">点击我不会跳转</a>

2. Prevent form submission

When the user submits the form, the browser will send the form data to the server and jump to the page returned by the server. Similarly, we can also process the form before it is submitted and prevent the default jump behavior. We can achieve this functionality by adding some JavaScript code in the form's onsubmit event.

For example, here is a form:

<form onsubmit="return false;">
  <input type="text" name="username">
  <input type="password" name="password">
  <button type="submit">提交</button>
</form>

By adding "return false;" to the onsubmit event, you can prevent the form's default submission behavior.

Similarly, you can also use the event.preventDefault() method to prevent the default submission behavior. For example:

<form>
  <input type="text" name="username">
  <input type="password" name="password">
  <button type="submit" onclick="event.preventDefault();">提交</button>
</form>

3. Prevent route jumps

In addition to preventing the default jump behavior on links and forms, we can also prevent route jumps through JavaScript. In the browser, we can get the URL of the current page through the location attribute of the window object and modify it to jump.

For example, we can change the URL of the current page to the URL of another page to achieve routing jump:

window.location.href = "http://www.example.com";

If we want to process before the jump, such as form data For verification, conditional judgments can be added to the code.

For example, the following is a form:

<form>
  <input type="text" name="username">
  <input type="password" name="password">
  <button type="button" onclick="checkForm()">提交</button>
</form>

Call the checkForm() function in the onclick event. In this function, the form data can be verified. If the verification fails, no jump will be performed.

function checkForm() {
  // 表单数据验证
  if (验证失败) {
    return;
  }
  window.location.href = "http://www.example.com";
}

Summary

In web development, preventing route jumps is a very common operation. We can implement this functionality in links, forms and code through JavaScript. By preventing route jumps, we can perform some processing or checks after the user clicks a link or submits a form to avoid data loss or security issues caused by user misoperation.

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