@putout/plugin-regexp

Regular expressions are patterns used to match character combinations in strings.

(c) MDN

🐊Putout plugin helps with Regular Expressions.

Install

npm i @putout/plugin-regexp -D

Rules

• ✅ apply-character-class;
• ✅ apply-ends-with;
• ✅ apply-global-regexp-to-replace-al;
• ✅ apply-literal-notation;
• ✅ apply-starts-with;
• ✅ convert-replace-to-replace-all;
• ✅ convert-to-string;
• ✅ optimize;
• ✅ remove-useless-group;
• ✅ remove-useless-regexp;
• ✅ remove-useless-escape;
• ✅ remove-duplicates-from-character-class;

Config

{
    "rules": {
        "regexp/apply-character-class": "on",
        "regexp/apply-global-regexp-to-replace-all": "on",
        "regexp/apply-literal-notation": "on",
        "regexp/apply-starts-with": "on",
        "regexp/apply-ends-with": "on",
        "regexp/optimize": "on",
        "regexp/convert-to-string": "on",
        "regexp/convert-replace-to-replace-all": "on",
        "regexp/remove-useless-group": "on",
        "regexp/remove-useless-escape": "on",
        "regexp/remove-useless-regexp": "on",
        "regexp/remove-duplicates-from-character-class": "on"
    }
}

optimize

❌ Example of incorrect code

const a = /(ab|ab)/;

✅ Example of correct code

const a = /(ab)/;

apply-character-class

Checkout in:

• 🐊Putout Editor.
• AST Explorer.

❌ Example of incorrect code

/\)|\(/g;

✅ Example of correct code

/[)(]/g;

apply-global-regexp-to-replace-all

Uncaught TypeError: String.prototype.replaceAll called with a non-global RegExp argument

(c) MDN

Checkout in 🐊Putout Editor.

❌ Example of incorrect code

's'.replaceAll(/hello/, 's');
'abc'.matchAll(/./);

✅ Example of correct code

's'.replaceAll(/hello/g, 's');
'abc'.matchAll(/./g);

apply-literal-notation

❌ Example of incorrect code

const a = new RegExp('hello', 'i');

✅ Example of correct code

const a = /hello/i;

apply-starts-with

The startsWith() method determines whether a string begins with the characters of a specified string, returning true or false as appropriate.

(c) MDN

RegExp is overkill for such a simple task as determining that string located at the beginning. Check it out in 🐊 Putout Editor.

❌ Example of incorrect code

/^hello/.test(a);

✅ Example of correct code

a.startsWith('hello');

Comparison

Linter | Rule | Fix --------|-------|------------| 🐊 Putout| regexp/apply-starts-with| ✅ 🦕 TypeScript ESLint | prefer-string-starts-ends-with | ✅

apply-ends-with

The startsWith() method determines whether a string ends with the characters of a specified string, returning true or false as appropriate.

(c) MDN

RegExp is overkill for such a simple task as determining that string located at the end.

❌ Example of incorrect code

/hello$/.test(a);

✅ Example of correct code

a.endsWith('hello');

Comparison

Linter | Rule | Fix --------|-------|------------| 🐊 Putout| regexp/apply-ends-with| ✅ 🦕 TypeScript ESLint | prefer-string-starts-ends-with | ✅

convert-to-string

❌ Example of incorrect code

'hello'.replace(/hello/, 'world');

✅ Example of correct code

'hello'.replace('hello', 'world');

convert-replace-to-replace-all

Simplify code according to string-replace-all.

❌ Example of incorrect code

'hello'.replace(/hello/g, 'world');

✅ Example of correct code

'hello'.replaceAll('hello', 'world');

remove-useless-group

❌ Example of incorrect code

/(hello)/.test(str);

✅ Example of correct code

/hello/.test(str);

remove-useless-escape

Checkout in 🐊Putout Editor.

❌ Example of incorrect code

const cleanText = code.replaceAll(/[,;\(\)]/g, '');

✅ Example of correct code

const cleanText = code.replaceAll(/[,;()]/g, '');

Comparison

Linter | Rule | Fix --------|-------|------------| 🐊 Putout| regexp/remove-useless-escape| ✅ ⏣ ESLint | no-useless-escape | ❌

remove-useless-regexp

❌ Example of incorrect code

const a = /^\.hello$/.test(str);

✅ Example of correct code

const a = str === '.hello';

remove-duplicates-from-character-class

Checkout in AST Explorer.

❌ Example of incorrect code

/[aaabb]/.test(str);

✅ Example of correct code

/[ab]/.test(str);

License

MIT