When submitting data using the value attribute correctly, you should clearly set the value value of each option, so that the data submitted to the server when the user selects the option is the set value. For example, define three options in the form as red, green and blue, and set the value to r, g, and b, then submit color=r when red is selected; if value is not set manually, the text between the labels will be used as the submission value by default, such as color=red. There are three advantages to using the value attribute: 1. Submitting data is more concise; 2. The unified format is convenient for background processing; 3. The actual content can be hidden and friendly names can be displayed. Common misunderstandings include confusing the function of name and value. Name is used to identify the select element, value represents the currently selected specific value, and the final submission structure is name=value. Notes also include avoiding multiple options using the same value, preventing the backend from handling exceptions, and ensuring that the backend pays attention to case and spaces when receiving to avoid matching failure.

In HTML, the value attribute of the <option></option> tag determines the data actually submitted to the server when the user selects this option. If you do not set value manually, the text content between <option></option> tags will be used by default as the submission value.

How to correctly submit data using value

When you have a drop-down menu ( <select></select> element), each <option></option> can set a value attribute. After selecting an option, this value will be submitted with the form.

For example:

 <form action="/submit" method="post">
  <label for="color">Select color:</label>
  <select name="color" id="color">
    <option value="r">Red</option>
    <option value="g">Green</option>
    <option value="b">Blue</option>
  </select>
  <button type="submit">Submit</button>
</form>

In this example, if the user selects "red", the data submitted by the form is color=r . If no value is set, it will be color=紅色.

Why should value attribute be used?

• More concise : Some display text may be long and are not suitable for direct use as submission values.
• Unified format : convenient for background processing, such as using short code instead of long strings.
• Hide information : Do not want users to see the actual submitted content, but also want the front-end to display a friendly name.

For example:

 <option value="user_001">Zhang San</option>

The submitted is user_001 , but the page shows "Zhang San".

Common misunderstandings and precautions

Sometimes developers will confuse the role of name and value :

• name is the identifier name of the entire <select></select> , used for the key when submitting the form.
• value is the value corresponding to the currently selected <option></option> .

So the final submitted data is a structure like name=value .

There are a few more points to note:

• If multiple <option></option> are set to the same value , the backend may only take the first or last one, depending on the implementation.
• Don't miss value , otherwise the browser will automatically use the display text, which may lead to unexpected problems.
• When receiving data in the backend, pay attention to format problems such as uppercase and lowercase case and space to avoid matching failure.

Let's summarize

Use value attribute to allow <option></option> to send the data you specified when submitting, rather than directly using the displayed text. This is very practical in development, especially when unified data formats or simplified backend logic is required.

Basically all that, although it seems simple, it is often overlooked or misused in actual projects.

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