element-dataset/src/index.js

/* eslint-disable prefer-reflect, camelcase */

'use strict'

module.exports = function () {
	if (!document.documentElement.dataset &&
		(
			!Object.getOwnPropertyDescriptor(Element.prototype, 'dataset')  ||
			!Object.getOwnPropertyDescriptor(Element.prototype, 'dataset').get
		)
	) {
		const descriptor = {}

		descriptor.enumerable = true

		descriptor.get = function () {
			const element = this
			const map = {}
			const attributes = this.attributes

			function toUpperCase (n0) {
				return n0.charAt(1).toUpperCase()
			}

			function getter () {
				return this.value
			}

			function setter (name, value) {
				if (typeof value !== 'undefined') {
					this.setAttribute(name, value)
				}
				else {
					this.removeAttribute(name)
				}
			}

			for (let index = 0; index < attributes.length; index++) {
				const attribute = attributes[index]

				// This test really should allow any XML Name without
				// colons (and non-uppercase for XHTML)

				if (attribute && attribute.name && (/^data-\w[\w\-]*$/).test(attribute.name)) {
					const name = attribute.name
					const value = attribute.value

					// Change to CamelCase

					const propName = name.substr(5).replace(/-./g, toUpperCase)

					Object.defineProperty(map, propName, {
						enumerable: this.enumerable,
						get: getter.bind({value: value || ''}),
						set: setter.bind(element, name)
					})
				}
			}
			return map
		}

		Object.defineProperty(Element.prototype, 'dataset', descriptor)
	}
}