eslint-plugin-lodash-template

ESLint plugin for John Resig-style micro templating.

It can be used in projects using Underscore.js and Lodash's template.

This plugin supports code checking for templates like the examples below.

<div id="<%= id %>" class="<%= (i % 2 == 1 ? ' even': '') %>">
  <div class="grid_1 alpha right">
    <img class="righted" src="<%= profile_image_url %>"/>
  </div>
  <div class="grid_6 omega contents">
    <p><b><a href="/<%= from_user %>"><%= from_user %></a>:</b> <%= text %></p>
  </div>
</div>

<% for ( var i = 0; i < users.length; i++ ) { %>
  <li><a href="<%= users[i].url %>"><%= users[i].name %></a></li>
<% } %>

Playground on the Web

output sample(on SublimeText):

Features

Enable ESLint in Underscore.js and Lodash's templates.
You can find issues specific to template tags.
Improves readability of HTML templates.
For JavaScript (TypeScript) templates, enable ESLint both inside and outside the template tag. (This is an experimental feature)
Partial supports for EJS.

Installation

npm install --save-dev eslint eslint-plugin-lodash-template

Documentation

See documents.

Usage

Create .eslintrc.* file to configure rules. See also: http://eslint.org/docs/user-guide/configuring.

Example eslint.config.js:

import lodashTemplate from 'eslint-plugin-lodash-template'
export default [
    {
        files: ['**/*.html'],
        ...lodashTemplate.configs['flat/recommended-with-html']
    }
]

Example .eslintrc.js:

module.exports = {
  extends: [
    // add more generic rulesets here, such as:
    // 'eslint:recommended',
    'plugin:lodash-template/recommended-with-html'
  ],
  rules: {
    // override/add rules settings here, such as:
    // 'lodash-template/no-warning-html-comments': 'error'
  }
}

Attention

This plugin does special handling for the following rule warnings in the template.

Rule ID	Process Description	Another way this plugin supports
`indent`	Disable warnings	`lodash-template/scriptlet-indent` rule, `lodash-template/html-indent`rule
`@stylistic/indent`	Disable warnings	`lodash-template/scriptlet-indent` rule, `lodash-template/html-indent` rule
`strict`	Disable warnings	--
`no-empty`	Disable warnings	--
`max-statements-per-line`	Disable warnings	--
`@stylistic/max-statements-per-line`	Disable warnings	--
`padded-blocks`	Disable warnings	--
`@stylistic/padded-blocks`	Disable warnings	--
`no-implicit-globals`	Disable warnings	--
`no-multi-spaces`	Disable warnings	`lodash-template/no-multi-spaces-in-scriptlet` rule, `lodash-template/no-multi-spaces-in-html-tag` rule
`@stylistic/no-multi-spaces`	Disable warnings	`lodash-template/no-multi-spaces-in-scriptlet` rule, `lodash-template/no-multi-spaces-in-html-tag` rule
`no-unused-expressions`	Disable warnings within interpolate(<%=...%>)	--
`quotes`	Disable warnings if doublequote is set	--
`@stylistic/quotes`	Disable warnings if doublequote is set	--
`no-irregular-whitespace`	Disable warnings outside template tags	`lodash-template/no-irregular-whitespace` rule

Configs

For `eslint.config.js`

This plugin provides 7 predefined configs:

*.configs['flat/base'] - Settings and rules to enable correct ESLint parsing
*.configs['flat/base-with-ejs'] - Settings and rules to enable correct ESLint parsing for EJS
*.configs['flat/best-practices'] - Above, plus rules to improve dev experience
*.configs['flat/recommended'] - Above, plus rules to improve code readability
*.configs['flat/recommended-with-html'] - Above, plus rules to improve code readability with HTML template
*.configs['flat/recommended-with-script'] - *.configs['flat/recommended'] config, plus to enable ESLint parsing of JavaScript templates (This is an experimental feature)
*.configs['flat/all'] - All rules of this plugin are included

For `.eslintrc.*`

This plugin provides 6 predefined configs:

plugin:lodash-template/base - Settings and rules to enable correct ESLint parsing
plugin:lodash-template/best-practices - Above, plus rules to improve dev experience
plugin:lodash-template/recommended - Above, plus rules to improve code readability
plugin:lodash-template/recommended-with-html - Above, plus rules to improve code readability with HTML template
plugin:lodash-template/recommended-with-script - plugin:lodash-template/recommended config, plus to enable ESLint parsing of JavaScript templates (This is an experimental feature)
plugin:lodash-template/all - All rules of this plugin are included

Rules

The --fix option on the command line automatically fixes problems reported by rules which have a wrench 🔧 below.

Base Rules (Enabling Correct ESLint Parsing)

Enable this plugin using with:

{
  "extends": "plugin:lodash-template/base"
}

	Rule ID	Description
	lodash-template/no-script-parsing-error	disallow parsing errors in template

Best Practices (Improve Development Experience)

Enforce all the rules in this category with:

{
  "extends": "plugin:lodash-template/best-practices"
}

	Rule ID	Description
	lodash-template/no-empty-template-tag	disallow empty micro-template tag. (ex. 🆖 `<% %>`)
	lodash-template/no-invalid-template-interpolation	disallow other than expression in micro-template interpolation. (ex. 🆖 `<%= if (test) { %>`)
🔧	lodash-template/no-semi-in-template-interpolation	disallow the semicolon at the end of expression in micro template interpolation.(ex. 🆗 `<%= text %>` 🆖 `<%= text; %>`)

Recommended (Improve Readability)

Enforce all the rules in this category and all the rules in Best Practices categories with:

{
  "extends": "plugin:lodash-template/recommended"
}

	Rule ID	Description
🔧	lodash-template/no-irregular-whitespace	disallow irregular whitespace outside the template tags.
🔧	lodash-template/no-multi-spaces-in-scriptlet	disallow multiple spaces in scriptlet. (ex. 🆖 `<% if···(test)···{ %>`)
🔧	lodash-template/scriptlet-indent	enforce consistent indentation to scriptlet in micro-template tag.
🔧	lodash-template/template-tag-spacing	enforce unified spacing in micro-template tag. (ex. 🆗 `<%= prop %>`, 🆖 `<%=prop%>`)

Recommended with HTML template (Improve Readability with HTML template)

Enforce all the rules in this category and all the rules in Best Practices/Recommended categories with:

{
  "extends": "plugin:lodash-template/recommended-with-html"
}

	Rule ID	Description
🔧	lodash-template/attribute-name-casing	enforce HTML attribute name casing. (ex. 🆗 `<div foo-bar>` 🆖 `<div fooBar>` `<div FOO-BAR>`)
🔧	lodash-template/attribute-value-quote	enforce quotes style of HTML attributes. (ex. 🆗 `<div class="abc">` 🆖 `<div class='abc'>` `<div class=abc>`)
🔧	lodash-template/element-name-casing	enforce HTML element name casing. (ex. 🆗 `<xxx-element>` 🆖 `<xxxElement>` `<DIV>`)
🔧	lodash-template/html-closing-bracket-newline	require or disallow a line break before tag's closing brackets
🔧	lodash-template/html-closing-bracket-spacing	require or disallow a space before tag's closing brackets. (ex. 🆗 `<input>` `<input·/>` 🆖 `<input·>` `<input/>`)
🔧	lodash-template/html-comment-content-newline	require or disallow a line break before and after HTML comment contents
🔧	lodash-template/html-comment-spacing	enforce unified spacing in HTML comment. (ex. 🆗 `<!-- comment -->`, 🆖 `<!--comment-->`)
🔧	lodash-template/html-content-newline	require or disallow a line break before and after HTML contents
🔧	lodash-template/html-indent	enforce consistent HTML indentation.
🔧	lodash-template/max-attributes-per-line	enforce the maximum number of HTML attributes per line
	lodash-template/no-duplicate-attributes	disallow duplication of HTML attributes. (ex. 🆖 `<div foo foo>`)
	lodash-template/no-html-comments	disallow HTML comments. (ex. 🆖 `<!-- comment -->`)
🔧	lodash-template/no-multi-spaces-in-html-tag	disallow multiple spaces in HTML tags. (ex. 🆖 `<input···type="text">`)
🔧	lodash-template/no-space-attribute-equal-sign	disallow spacing around equal signs in attribute. (ex. 🆗 `<div class="item">` 🆖 `<div class = "item">`)
	lodash-template/no-warning-html-comments	disallow specified warning terms in HTML comments. (ex. 🆖 `<!-- TODO:task -->`)

Uncategorized

	Rule ID	Description
	lodash-template/no-template-tag-in-start-tag	disallow template tag in start tag outside attribute values. (ex. 🆖 `<input <%= 'disabled' %> >`)
	lodash-template/prefer-escape-template-interpolations	prefer escape micro-template interpolations. (ex. 🆗 `<%- ... %>`, 🆖 `<%= ... %>`)

Plugin Option

Suppress `no-undef` warnings in the template tag

Please set the global variable used in all templates as follows.

.eslintrc.*:

  {
      "settings": {
+         "lodash-template/globals": ["variableName"]
      }
  }

Please write the global comment in the file as follows for the variable to be used with a specific template.

+ <% /* global users */ %>
  <% for ( var i = 0; i < users.length; i++ ) { %>
    <li><a href="<%= users[i].url %>"><%= users[i].name %></a></li>
  <% } %>

Suppress reports for specific rules in template files

Please set as follows.

.eslintrc.*:

  {
      "settings": {
+         "lodash-template/ignoreRules": ["no-undef", "no-tabs"]
      }
  }

The ESLint standard suppression method can also be used by using template tag, as follows.

+ <% /* eslint no-ternary: 0 */ %>

Customize parser

For example, if you set Lodash templateSettings as follows,

_.templateSettings = {
    evaluate:    /{{([\s\S]+?)}}/g,
    interpolate: /{{=([\s\S]+?)}}/g,
    escape:      /{{-([\s\S]+?)}}/g
};

please set parserOptions(ex. .eslintrc.*) as follows.

      parserOptions: {
+         templateSettings: {
+             evaluate:    ["{{", "}}"],
+             interpolate: ["{{=", "}}"],
+             escape:      ["{{-", "}}"],
+         },
      },

For example, to parse like EJS, set as follows,

(If plugin:lodash-template/*** is set in extends, it is automatically applied to the extension .ejs.)

      parserOptions: {
+         templateSettings: {
+             evaluate:    [ ["<%", "<%_"], ["%>", "-%>", "_%>"] ],
+             interpolate: [  "<%-",        ["%>", "-%>", "_%>"] ],
+             escape:      [  "<%=",        ["%>", "-%>", "_%>"] ],
+             comment:     [  "<%#",        ["%>", "-%>", "_%>"] ],
+             literal:     [  "<%%" ],
+         },
      },

(This plugin do not provide complete support for EJS. e.g. the include directive.)

Customize target extensions

Please set .eslintrc.* as follows.

(For example, for EJS.)

+    "overrides": [
+        {
+            "files": ["*.ejs"],
+            "processor": "lodash-template/html"
+        }
+    ]

For JavaScript (TypeScript) Templates

(This is an experimental feature. Also check for known limitations.)

For example if you have a file like below.

/* eslint no-multi-spaces: error */
<% /* eslint lodash-template/no-multi-spaces-in-scriptlet: error */ %>

// if this plugin is not used, a parsing error will occur.
const obj    = <%= JSON.stringify(options     ) %>
//       ^^^^                            ^^^^^ 
//         |                              |
//         |          If you don't use `"plugin:lodash-template/recommended-with-script"`,
//         |          only the space after `options` is reported.
//         |
//         + When using `"plugin:lodash-template/recommended-with-script"`, the space after `obj` is also reported.

Playground on the Web

Configuring

Please set .eslintrc.* as follows.

+    "overrides": [
+        {
+            "files": ["**/your/templates/*.js"],
+            "extends": ["plugin:lodash-template/recommended-with-script"]
+        }
+    ]

If you do not want to use the included rules, set the details as follows.

    "overrides": [
        {
            "files": ["**/your/templates/*.js"],
-            "extends": ["plugin:lodash-template/recommended-with-script"],
+            "extends": ["plugin:lodash-template/base"],
+            "processor": "lodash-template/script",
+            "rules": {
+                "lodash-template/no-invalid-template-interpolation": "error"
+                ...
+            }
        }
    ]

If you want to use it with TypeScript, you need to configure parserOptions.

    "overrides": [
        {
-            "files": ["**/your/templates/*.js"],
+            "files": ["**/your/templates/*.ts"],
+            "parserOptions": {
+                 "parser": "@typescript-eslint/parser",
+                 "sourceType": "module"
+            },
            "extends": ["plugin:lodash-template/recommended-with-script"]
        }
    ]

FAQ

Known Limitations in Script Templates

Due to known limitations in script templates, you may need to rewrite some templates. Otherwise, you may not be able to use this plugin or some rules.

Parsing Error

Interpolation in the script template will try to replace it with an identifier and parse it. If you generate a complex script in interpolation, you may get a parsing error.

👍 The following script can be parsed well.

let <%= idName %> = 42;
export { <%= idName %> };

👎 The following script cannot be parsed well.

<%= 'let ' + idName %> = 42;
export { <%= idName %> };

False Positives in Some Rules

If you use branching in your template, the plugin will generate multiple script ASTs needed to cover all branches. (Then merge the results of validating these ASTs.)
This can confuse some rules and cause false positives.

However, this is necessary to avoid script parsing errors.

e.g.

Template:

const a = 'foo'
<% if (x) { %>
  const b = 1;
<% } else { %>
  const b = 2;
<% } %>

Generated Script 1:

const a = 'foo'

  const b = 1;

Generated Script 2:

const a = 'foo'



  const b = 2;

If we use the following script, it is a parsing error.

const a = 'foo'

  const b = 1;

  const b = 2; // <- Identifier 'b' has already been declared

The plugin also tries to generate scripts using branches that are as consistent as possible.

e.g.

Template:

<% if (x.foo) { %>
  const a = 'x.foo is true'
<% } %>
// ...
<% if (x.foo) { %>
  console.log(a)
<% } else { %>
  // process for x.foo is false
<% } %>

Generated Script 1:

  const a = 'x.foo is true'

// ...

  console.log(a)

Generated Script 2:

// ...



  // process for x.foo is false

However, branching conditions are compared using text, so even logically the same can be confusing.

e.g.

Template:

<% if (x['foo']) { %>
  const a = 'x.foo is true'
<% } %>
// ...
<% if (x.foo) { %>
  console.log(a)
<% } else { %>
  // process for x.foo is false
<% } %>

Generated Script 1:

  const a = 'x.foo is true'

// ...

  console.log(a)

Generated Script 2:

  const a = 'x.foo is true'

// ...



  // process for x.foo is false

This template gets an error 'a' is assigned a value but never used. from the no-unused-vars rule.

Editor Settings with HTML templates

About how to mark warnings on editor.

VSCode (VS Code ESLint extension)

settings.json:

{
    "eslint.validate": [ "javascript", "javascriptreact", "html" ]
}

Sublime Text3 (SublimeLinter-eslint)

[Preference] > [Package Settings] > [SublimeLinter] > [Settings]

// SublimeLinter Settings - User
{
    "linters": {
        "eslint": {
            "selector": "text.html, source.js - meta.attribute-with-value"
        }
    }
}

Migrations

0.13.x to 0.14.x

Contributing

Welcome contributing!

Please use GitHub's Issues/PRs.

`parserServices`

Information provided by parserServices on this plugin

Development Tools

npm test runs tests and measures coverage.
npm run update runs in order to update readme and recommended configuration.

License

See the LICENSE file for license rights and limitations (MIT).

Name		Name	Last commit message	Last commit date
Latest commit History 405 Commits
.changeset		.changeset
.devcontainer		.devcontainer
.github/workflows		.github/workflows
.vscode		.vscode
docs		docs
images		images
lib		lib
samples		samples
test_sp		test_sp
tests		tests
tests_fixtures		tests_fixtures
tools		tools
.editorconfig		.editorconfig
.eslintignore		.eslintignore
.eslintrc.js		.eslintrc.js
.gitignore		.gitignore
.npmrc		.npmrc
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
README.md		README.md
logo.png		logo.png
logo.svg		logo.svg
package.json		package.json
renovate.json		renovate.json

License

ota-meshi/eslint-plugin-lodash-template

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eslint-plugin-lodash-template

Features

Installation

Documentation

Usage

Attention

Configs

For eslint.config.js

For .eslintrc.*

Rules

Base Rules (Enabling Correct ESLint Parsing)

Best Practices (Improve Development Experience)

Recommended (Improve Readability)

Recommended with HTML template (Improve Readability with HTML template)

Uncategorized

Plugin Option

Suppress no-undef warnings in the template tag

Suppress reports for specific rules in template files

Customize parser

Customize target extensions

For JavaScript (TypeScript) Templates

Configuring

FAQ

Known Limitations in Script Templates

Parsing Error

False Positives in Some Rules

Editor Settings with HTML templates

Migrations

Contributing

parserServices

Development Tools

License

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Releases 30

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Contributors 6

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For `eslint.config.js`

For `.eslintrc.*`

Suppress `no-undef` warnings in the template tag

`parserServices`

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