lindell / JsBarcode

import { EAN13_STRUCTURE } from './constants';

import EAN from './EAN';

// Calculate the checksum digit

// https://en.wikipedia.org/wiki/International_Article_Number_(EAN)#Calculation_of_checksum_digit

const checksum = (number) => {

	const res = number

		.substr(0, 12)

		.split('')

		.map((n) => +n)

		.reduce((sum, a, idx) => (

			idx % 2 ? sum + a * 3 : sum + a

		), 0);

	return (10 - (res % 10)) % 10;

};

class EAN13 extends EAN {

	constructor(data, options) {

		// Add checksum if it does not exist

		if (data.search(/^[0-9]{12}$/) !== -1) {

			data += checksum(data);

		}

		super(data, options);

		// Adds a last character to the end of the barcode

		this.lastChar = options.lastChar;

	}

	valid() {

		return (

			this.data.search(/^[0-9]{13}$/) !== -1 &&

			+this.data[12] === checksum(this.data)

		);

	}

	leftText() {

		return super.leftText(1, 6);

	}

	leftEncode() {

		const data = this.data.substr(1, 6);

		const structure = EAN13_STRUCTURE[this.data[0]];

		return super.leftEncode(data, structure);

	}

	rightText() {

		return super.rightText(7, 6);

	}

	rightEncode() {

		const data = this.data.substr(7, 6);

		return super.rightEncode(data, 'RRRRRR');

	}

	// The "standard" way of printing EAN13 barcodes with guard bars

	encodeGuarded() {

		const data = super.encodeGuarded();

		// Extend data with left digit & last character

		if (this.options.displayValue) {

			data.unshift({

				data: '000000000000',

				text: this.text.substr(0, 1),

				options: { textAlign: 'left', fontSize: this.fontSize }

			});

			if (this.options.lastChar) {

				data.push({

					data: '00'

				});

				data.push({

					data: '00000',

					text: this.options.lastChar,

					options: { fontSize: this.fontSize }

				});

			}

		}

		return data;

	}

}

export default EAN13;