JavaScript Variable Name Validator

Validate any string as a JavaScript variable name, taking into consideration both the ECMAScript 6 specification and Unicode 8.0.0, as well as reserved words and invalid escape sequences in older engines.

Adapted from JavaScript identifier validator by Mathias Bynens and repackaged as an npm module.

Installation

Using npm

npm install validate-variable

Using yarn

yarn add validate-variable

Importing

Import as an ES6 module

import validateVariable, { isValidVariable } from 'validate-variable'

Import as a CommonJS module

const { validateVariable, isValidVariable } = require('validate-variable')

Basic usage

console.log(isValidVariable('ಠ_ಠ'))

Returning:

true

Advanced usage

Includes any errors and/or warnings with the return value.

With errors

console.log(validateVariable('await'))

Returning:

{
	valid: false,
	errors: {
		reserved: true
	}
}

With warnings

console.log(validateVariable('undefined'))

Returning:

{
	valid: true,
	warnings: {
		immutable: true
	}
}

Types of errors

invalidIdentifier

The format of the variable name is invalid according to ES6 + Unicode 8.0.0

reserved

The variable matches any reserved keywords like return or await

Types of warnings

es3

The variable is an ES3 reserved word. You may want to avoid using it if support for older JavaScript engines is a concern.

es5

Invalid identifier as per ES5. You may want to avoid using it if support for older JavaScript engines is a concern.

zeroWidth

The variable contains zero-width characters that are allowed in IdentifierPart as per ES5, but not in ES3. You may want to avoid using it if support for older JavaScript engines is a concern.

unicode

Invalid identifier according to Unicode v5.1.0. You may want to avoid using it if support for JavaScript engines with outdated Unicode data tables is a concern.

immutable

The NaN, Infinity, and undefined properties of the global object are immutable or read-only. Setting them won’t have an effect. Avoid using them as variable names.

Strict mode

Activate strict mode by setting the second argument to true when calling either method. This makes any warnings return an invalid result.

console.log(isValidVariable('NaN', true))

Returning:

false

License

Licensed under the GPL 2.0 license.