使用代碼驗(yàn)證工具能檢查HTML是否符合標(biāo)準(zhǔn)並找出錯(cuò)誤。要使用在線驗(yàn)證工具，可訪問W3C等網(wǎng)站粘貼或上傳代碼點(diǎn)擊驗(yàn)證，工具會(huì)逐行列出錯(cuò)誤及原因。常見錯(cuò)誤包括缺少閉合標(biāo)籤、嵌套錯(cuò)誤、自閉標(biāo)籤使用不當(dāng)和屬性拼寫錯(cuò)誤。定期驗(yàn)證代碼有助於保持HTML結(jié)構(gòu)的正確性。

You've written some HTML code and want to make sure it's clean and error-free — that's where a code validator comes in handy. Using one is straightforward, and it can save you from headaches later on when your page doesn't behave as expected.

What a Code Validator Does

A code validator checks your HTML against web standards set by organizations like the W3C (World Wide Web Consortium). It scans for syntax issues, missing tags, incorrect nesting, and other common mistakes that might break your layout or functionality. Think of it like spellcheck but for your website markup.

Most validators give you line-by-line feedback so you can pinpoint exactly where something went wrong. This helps especially when dealing with large files or complex structures.

How to Use an Online Validator

The easiest way to validate HTML is through online tools like the W3C Markup Validation Service . Here's how to use it:

• Go to the validator website
• Paste your HTML code into the provided box or upload the file directly
• Click “Check” or “Validate”

Within seconds, the tool will return a list of errors and warnings. Each entry usually includes the line number and a brief explanation. Some validators even let you check live URLs if you're working with a published site.

If you see a message like “Start tag seen without seeing a doctype first,” it means your declaration is missing or misplaced — a small fix that could prevent major rendering issues.

Common Errors You'll Catch

Some problems pop up more than others. For example:

• Missing closing tags ( or )
• Incorrectly nested elements
• Improper use of self-closing tags (like <img alt="如何使用代碼驗(yàn)證器檢查我的HTML代碼是否錯(cuò)誤？" > instead of <img alt="如何使用代碼驗(yàn)證器檢查我的HTML代碼是否錯(cuò)誤？" > in XHTML)
• Misspelled or unsupported attributes

One frequent mistake is forgetting to close anchor tags before starting a new block-level element inside them — browsers might render this oddly, but a validator will flag it clearly.

Also, if you're copying code snippets from elsewhere, there's a chance they contain invalid characters or deprecated tags. The validator will highlight these too.

That's basically how it works. Run your code through a validator early and often — it's a quick habit that keeps your HTML solid.

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