hasClass, addClass, removeClass, toggleClass implementation in ES6

class-utils.js

/**
 *
 * @param classNames
 * @param className
 * @returns {boolean}
 */
export function hasClass(classNames, className) {
	return new RegExp(` ${className} `).test(` ${classNames} `)
}

/**
 *
 * @param classNames
 * @param className
 * @returns {*}
 */
export function addClass(classNames, className) {
	let output = classNames

	if (!hasClass(classNames, className)) {
		output = `${classNames}  ${className}`
	}

	return output
}

/**
 *
 * @param classNames
 * @param className
 * @returns {string}
 */
export function removeClass(classNames, className) {
	let output = ` ${classNames.replace(/[\t\r\n]/g, ' ')} `

	if (hasClass(classNames, className)) {
		while (output.indexOf(` ${className} `) >= 0) {
			output = output.replace(` ${className} `, ' ')
		}

		output = output.replace(/^\s+|\s+$/g, '')

		return output
	}
}

/**
 *
 * @param classNames
 * @param className
 * @returns {string}
 */
export function toggleClass(classNames, className) {
	let output = ` ${classNames.replace( /[\t\r\n]/g, ' ')} `

	if (hasClass(classNames, className)) {
		while (output.indexOf(` ${className} `) >= 0) {
			output = output.replace(` ${className} `, ' ')
		}

		output = output.replace(/^\s+|\s+$/g, '')
	} else {
		output += ` ${className}`
	}

	return output
}