Creating Fixable Rule

textlint has linter and also has fixer.

export default function reporter(context) {}

is shorthand function syntax of

function reporter(context) {}
export default {
    linter: reporter
};

ℹ️ You should know Creating Rules in advance.

Now, you can implement fixer like that:

function reporter(context) {
    // report error and fix command
}
export default {
    linter: reporter,
    fixer: reporter
};

fixer does lint and found error

If you'd like textlint to attempt to fix the problem you're reporting, you can do so by specifying the fix object when using context.report(). The fixer object, that you can use to apply a fix. For example:

The fixer object has the following methods:

// TODO: more reasonable example
const reporter = (context) => {
    // `context.fixer`
    const { Syntax, RuleError, fixer, report, getSource } = context;
    return {
        [Syntax.Str](node) {
            const text = getSource(node);
            // "You fix this"
            //      ^^^
            const matchRegexp = /\bfix\b/;
            if (!matchRegexp.test(text)) {
                return;
            }
            // found "fixable" error
            const index = text.search(matchRegexp);
            const length = "fix".length;
            const replace = fixer.replaceTextRange([index, index + length], "fixed");
            report(
                node,
                new RuleError("Replaced", {
                    // "You fix this"
                    //      ^ index
                    index,
                    // "You fix this"
                    //      ^^^
                    //     fixed
                    fix: replace
                })
            );
        }
    };
};
export default {
    linter: reporter,
    // This rule has fixer.
    fixer: reporter
};

The context.fixer. object has the following methods:

• fixer.insertTextAfter(node, text) - inserts text after the given node
• fixer.insertTextAfterRange(range, text) - inserts text after the given range
• fixer.insertTextBefore(node, text) - inserts text before the given node
• fixer.insertTextBeforeRange(range, text) - inserts text before the given range
• fixer.remove(node) - removes the given node
• fixer.removeRange(range) - removes text in the given range
• fixer.replaceText(node, text) - replaces the text in the given node
• fixer.replaceTextRange(range, text) - replaces the text in the given range

Best practices for fixes:

1. Make fixes that are as small as possible. Anything more than a single character is risky and could prevent other, simpler fixes from being made.
2. Make one fix per message.

Publishing

You can publish fixable rule to npm that is the same way of a rule

Be careful to following points.

fixable feature is newer

Old textlint not support fixable feature, so old textlint don't understand fixable. As a result, old textlint throw error.

Error: Definition for rule 'rule-name' was not found.

We recommended that add peerDependencies to package.json

  "peerDependencies": {
    "textlint": ">= 5.5.0"
  }

Display fixable or not

If your textlint's rule is fixable, display "this rule is fixable!".

We have fixable rule badge and use it!

[![textlint rule](https://img.shields.io/badge/textlint-fixable-green.svg?style=social)](https://textlint.org/) 

Terms

• fixble rule: A rule report error that could be fixed
  • fixable is fix-able.