Asynchronous version of String.prototype.replace, using promises

replace-async.js

export default function replaceAsync(str, re, func) {
	let replacements = []
	str.replace(re, (...args) => {
		replacements.push(func(...args).then(res => [ args[args.length - 2], args[0].length, res ]))
	})
	return Promise.all(replacements).then(replacements => {
		let out = ''
		let lastEnd = 0
		for (let [ offset, length, replacement ] of replacements) {
			out += str.slice(lastEnd, offset) + replacement
			lastEnd = offset + length
		}
		out += str.slice(lastEnd)
		return out
	})
}