javascript - 错误类型错误 : Cannot read property '1' of null

Question

我正在尝试解析通过读卡器传递的卡数据，但是，我收到有关正则表达式的错误。我知道这意味着 this.match 为空，但我不确定为什么它为空。有什么建议么？ (使用 Angular 9)

    CardData: string;
    CardPattern = new RegExp("^\%B(\d+)\^(\w+)\/(\w+)\^\d+\?;\d+=(\d\d)(\d\d)\d+$");
    CardNumber: string;
    FirstName: string;
    LastName: string;
    ExpData: string;
    match: RegExpExecArray;

    constructor(private snackbar: SnackBar) {
    }

    ngOnInit() {
        // getaCardData();
        this.CardData = "%B6545461234613451^DOE/JOHN^00000000000000000000000?;6545461234613451=984651465116111?"

        this.match = this.CardPattern.exec(this.CardData);

        this.CardNumber = this.match[1]
        this.FirstName = this.match[3];
        this.LastName = this.match[2];
        this.ExpData = this.match[5] + "/" +this.match[4];

        console.log(this.CardNumber);
    }

Answer 1

您的模式不匹配，因为字符串末尾有一个附加字符 ?: this.CardData = %B6545461234613451^DOE/JOHN^00000000000000000000000?;6545461234613451=984651465116111?"

替换为:

this.CardData = "%B6545461234613451^DOE/JOHN^00000000000000000000000?;6545461234613451=984651465116111"

或者改变你的模式: ^\%B(\d+)\^(\w+)\/(\w+)\^\d+\?;\d+=(\d\d)(\d\d)\d+\?$

更新:添加了工作代码片段供您引用!尝试添加标志，它应该可以工作。

const regex = new RegExp(/^\%B(\d+)\^(\w+)\/(\w+)\^\d+\?;\d+=(\d\d)(\d\d)\d+\?$/, 'gm');
const input = `%B6545461234613451^DOE/JOHN^00000000000000000000000?;6545461234613451=984651465116111?`;
var match = regex.exec(input);

document.write(match.length);