forked from FOSS/BangleApps
55 lines
1.1 KiB
JavaScript
55 lines
1.1 KiB
JavaScript
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// Encoding documentation:
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// https://en.wikipedia.org/wiki/Universal_Product_Code#Encoding
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const encode = require("cards.encode.js");
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const Barcode = require("cards.Barcode.js");
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class UPC extends Barcode{
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constructor(data, options){
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// Add checksum if it does not exist
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if(data.search(/^[0-9]{11}$/) !== -1){
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data += checksum(data);
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}
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super(data, options);
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}
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valid(){
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return this.data.search(/^[0-9]{12}$/) !== -1 &&
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this.data[11] == checksum(this.data);
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}
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encode(){
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var result = "";
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result += "101";
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result += encode(this.data.substr(0, 6), "LLLLLL");
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result += "01010";
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result += encode(this.data.substr(6, 6), "RRRRRR");
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result += "101";
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return {
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data: result,
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text: this.text
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};
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}
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}
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// Calulate the checksum digit
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// https://en.wikipedia.org/wiki/International_Article_Number_(EAN)#Calculation_of_checksum_digit
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function checksum(number){
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var result = 0;
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var i;
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for(i = 1; i < 11; i += 2){
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result += parseInt(number[i]);
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}
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for(i = 0; i < 11; i += 2){
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result += parseInt(number[i]) * 3;
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}
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return (10 - (result % 10)) % 10;
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}
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module.exports = { UPC, checksum };
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