AngularJS service that takes a collection and returns a CSV file download

exportcsv.service.js

exportcsv.$inject = ['$sce']

function exportcsv($sce) {

	const defaultOptions = {
		filename: 'export'
	}

	return { toCSV }

	///////
	
	function toCSV(arrToExport, options = defaultOptions) {

		// returns an array of keys to be used as table header
		const header = Object.keys(arrToExport[0])

		const propObject = header.reduce( (prev, curr) => {
			prev[curr] = curr
			return prev
		}, {})

		arrToExport.unshift(propObject)

		const csvData = arrToExport
			.map( (obj) => {
				const item = Object.keys(obj)
					.map( (key) => [ `" ${obj[key]} ",` ] )
					.reduce( (prev, current) => prev.concat(current) )
				item.splice(item.length - 1, 1, "\n")
				return item
			})
			.reduce( (prev, current) => prev.concat(current) )
			.join('')

		// add BOM to make sure special characters are read correctly
		const BOM = "\uFEFF"
		const output = BOM + csvData
		const file = new Blob([output], { type: 'text/csv;charset=utf-8' })
		const url = $sce.trustAsResourceUrl(URL.createObjectURL(file))

		return function() {
			const a = document.createElement("a")
			a.href = url
			a.style = "display: none"
			a.download = options.filename + '.csv'
			a.click()
		}()
	}
}

export default exportcsv