Usage
Simply install via npm install --save-dev eslint-plugin-html
and add the plugin to your ESLint
configuration. See
ESLint documentation.
Example:
{
"plugins": [
"html"
]
}
Multiple scripts tags in a HTML file
When linting a HTML with multiple script tags, this plugin tries to emulate the browser behavior by
sharing the global scope between scripts by default. This behavior doesn't apply to "module"
scripts (ie: <script type="module">
and most transpiled code), where each script tag gets its own
top-level scope.
ESLint has already an
option to tell the parser
if the script are modules. eslint-plugin-html
will use this option as well to know if the scopes
should be shared (the default) or not. To change this, just set it in your ESLint configuration:
{
"parserOptions": {
"sourceType": "module"
}
}
To illustrate this behavior, consider this HTML extract:
<script>
var foo = 1;
</script>
<script>
alert(foo);
</script>
This is perfectly valid by default, and the ESLint rules no-unused-vars
and no-undef
shouldn't
complain. But if those scripts are considerated as ES modules, no-unused-vars
should report an
error in the first script, and no-undef
should report an error in the second script.
History
In eslint-plugin-html
v1 and v2, script code were concatenated and linted in a single pass, so
the scope were always shared. This caused some issues, so in v3 all scripts
were linted separately, and scopes were never shared. In v4, the plugin still lint scripts
separately, but makes sure global variables are declared and used correctly in the non-module case.
XML support
This plugin parses HTML and XML markup slightly differently, mainly when considering CDATA
sections:
- in XML, any data inside a
CDATA
section will be considered as raw text (not XML) and the CDATA
delimiter will be droped ; - in HTML, there is no such thing for
<script>
tags: the CDATA
delimiter is considered as normal
text and thus, part of the script.
Settings
Note: all settings can be written either as "html/key": value
or in a nested object "html": { "key": value }
html/html-extensions
By default, this plugin will only consider files ending with those extensions as HTML: .erb
,
.handlebars
, .hbs
, .htm
, .html
, .mustache
, .nunjucks
, .php
, .tag
, .twig
, .we
.
You can set your own list of HTML extensions by using this setting. Example:
{
"plugins": [ "html" ],
"settings": {
"html/html-extensions": [".html", ".we"],
}
}
html/xml-extensions
By default, this plugin will only consider files ending with those extensions as XML: .xhtml
,
.xml
. You can set your own list of XML extensions by using this setting. Example:
{
"plugins": [ "html" ],
"settings": {
"html/xml-extensions": [".html"],
}
}
html/indent
By default, the code between <script>
tags is dedented according to the first non-empty line. The
setting html/indent
allows to ensure that every script tags follow an uniform indentation. Like
the indent
rule, you can pass a number of spaces, or "tab"
to indent with one tab. Prefix this
value with a +
to be relative to the <script>
tag indentation. Example:
{
"plugins": [ "html" ],
"settings": {
"html/indent": "0",
"html/indent": "+2",
"html/indent": "tab",
}
}
html/report-bad-indent
By default, this plugin won't warn if it encounters a problematic indentation (ex: a line is under
indented). If you want to make sure the indentation is correct, use the html/report-bad-indent
in
conjunction with the indent
rule. Pass "warn"
or 1
to display warnings, "error"
or 2
to
display errors. Example:
{
"plugins": [ "html" ],
"settings": {
"html/report-bad-indent": "error",
}
}
html/javascript-mime-types
By default, the code between <script>
tags is considered as JavaScript code only if there is no
type
attribute or if its value matches the pattern
(application|text)/(x-)?(javascript|babel|ecmascript-6)
or module
(case insensitive). You can
customize the types that should be considered as JavaScript by providing one or multiple MIME types.
If a MIME type starts with a /
, it will be considered as a regular expression. Example:
{
"plugins": [ "html" ],
"settings": {
"html/javascript-mime-types": ["text/javascript", "text/jsx"],
"html/javascript-mime-types": "/^text\\/(javascript|jsx)$/",
}
}
Troubleshooting
No file linted when running eslint
on a directory
By default, when executing the eslint
command on a directory, only .js
files will be linted. You
will have to specify extra extensions with the --ext
option. Example: eslint --ext .html,.js src
will lint both .html
and .js
files in the src
directory. See ESLint
documentation.
Linting templates (or PHP)
eslint-plugin-html
won't evaluate or remove your template markup. If you have template markup in
your script tags, the resulting script may not be valid JavaScript, so ESLint
will fail to parse
it.
For PHP, you can use eslint-plugin-php-markup
to
lint php files, it use a same way to process php markup like eslint-plugin-html
.
Or another possible hacky workaround to make sure the code is valid JavaScript is to put your template
markup inside a comment. When the template is rendered, the generated JS code must start with a new
line, so it will be written below the comment. PHP example:
<script>
var mydata;
console.log(mydata);
</script>
Linting VUE files
Initially, eslint-plugin-vue
was using
eslint-plugin-html
to lint code inside script tags. Since v3, eslint-plugin-vue
is using its
own parser, so it is incompatible with eslint-plugin-html
. You should use eslint-plugin-vue
exclusively and remove eslint-plugin-html
from your dependencies if you still have it.
Migration from older versions
To v4
eslint-plugin-html
v4 requires at least ESLint v4.7. This is because a lot of internal changes
occured in ESLint v4.7, including a new API to support autofixing in
preprocessors.
If you are still using an older version of ESLint, please consider upgrading, or keep using
eslint-plugin-html
v3.
The big feature (and breaking change) in eslint-plugin-html
v4 is the ability to choose how scopes
are shared between script tags in the same HTML file.
To v3
If you are considering upgrading to v3, please read this guide.
Credits
A big thank you to @Bkucera for the logo image!