No byte-order mark (no-bom)

no-bom warns against having the byte-order mark (BOM) character at the beginning of a text file.

Why is this important?

Having the BOM character at the beginning of a file over the internet (especially HTML) can have some bad side effects on some browsers. The BOM character can be used to indicate the charset of the content is UTF-8 but this doesn’t mean it will be considered. For example, Internet Explorer 10 and 11 give a higher precedence to the HTTP header while previous versions gave the precedence to BOM for the encoding.

You can learn about other problems in this section.

What does the hint check?

This hint checks that all text-based media type files are served without the BOM character at the beginning.

Examples that trigger the hint

A text file (such as HTML) that starts with the BOM character U+FEFF will fail.

Examples that pass the hint

A text file (such as HTML) that doesn’t start with the BOM character U+FEFF will pass.

How to use this hint?

This package is installed automatically by webhint:

npm install hint --save-dev

To use it, activate it via the .hintrc configuration file:

{
    "connector": {...},
    "formatters": [...],
    "hints": {
        "no-bom": "error",
        ...
    },
    "parsers": [...],
    ...
}

Note: The recommended way of running webhint is as a devDependency of your project.

Further Reading

• Byte order mark (Wikipedia)
• The byte-order mark (BOM) in HTML