将用户输入字符串转换为正则表达式

我正在用HTML和JavaScript设计一个正则表达式测试器。用户将输入一个正则表达式，一个字符串，并通过单选按钮选择他们想要测试的函数(例如搜索，匹配，替换等)，当该函数以指定的参数运行时，程序将显示结果。自然会有额外的文本框用于替换额外的参数等等。

My problem is getting the string from the user and turning it into a regular expression. If I say that they don't need to have //'s around the regex they enter, then they can't set flags, like g and i. So they have to have the //'s around the expression, but how can I convert that string to a regex? It can't be a literal since its a string, and I can't pass it to the RegExp constructor since its not a string without the //'s. Is there any other way to make a user input string into a regex? Will I have to parse the string and flags of the regex with the //'s then construct it another way? Should I have them enter a string, and then enter the flags separately?

当前回答

在我的例子中，用户输入有时被分隔符包围，有时没有。所以我又加了一个案例。

var regParts = inputstring.match(/^\/(.*?)\/([gim]*)$/);
if (regParts) {
    // the parsed pattern had delimiters and modifiers. handle them. 
    var regexp = new RegExp(regParts[1], regParts[2]);
} else {
    // we got pattern string without delimiters
    var regexp = new RegExp(inputstring);
}

2014-03-31 14:15:20

其他回答

下面是一个处理自定义分隔符和无效标志的线性函数

// One liner var stringToRegex = (s, m) => (m = s.match(/^([\/~@;%#'])(.*?)\1([gimsuy]*)$/)) ? new RegExp(m[2], m[3].split('').filter((i, p, s) => s.indexOf(i) === p).join('')) : new RegExp(s); // Readable version function stringToRegex(str) { const match = str.match(/^([\/~@;%#'])(.*?)\1([gimsuy]*)$/); return match ? new RegExp( match[2], match[3] // Filter redundant flags, to avoid exceptions .split('') .filter((char, pos, flagArr) => flagArr.indexOf(char) === pos) .join('') ) : new RegExp(str); } console.log(stringToRegex('/(foo)?\/bar/i')); console.log(stringToRegex('#(foo)?\/bar##gi')); //Custom delimiters console.log(stringToRegex('#(foo)?\/bar##gig')); //Duplicate flags are filtered out console.log(stringToRegex('/(foo)?\/bar')); // Treated as string console.log(stringToRegex('gig')); // Treated as string

2021-03-22 18:13:49

我用eval来解决这个问题。

例如:

    function regex_exec() {

        // Important! Like @Samuel Faure mentioned, Eval on user input is a crazy security risk, so before use this method, please take care of the security risk. 
        var regex = $("#regex").val();

        // eval()
        var patt = eval(userInput);

        $("#result").val(patt.exec($("#textContent").val()));
    }

2019-07-16 07:06:36

使用JavaScript的RegExp对象构造函数。

var re = new RegExp("\\w+");
re.test("hello");

可以将标志作为第二个字符串参数传递给构造函数。详细信息请参见文档。

2009-05-17 14:24:36

这也适用于字符串无效或不包含标志等情况:

regExpFromString(q) { Let flags = q.replace(/.*\/([gimuy]*)$/， '$1'); If (flags === q) flags = "; Let pattern = (flags ?q.replace(新RegExp ('^/(.*?)/' + 旗帜 + '$'), '$ 1 '):问); try{返回新的RegExp(模式，标志);} catch (e){返回null;｝｝ console.log (regExpFromString (' \ \ bword \ \ b ')); console.log (regExpFromString(‘\ / \ \ bword \ \ b \ / gi '));

2016-09-09 07:51:19

尝试使用下面的函数:

const stringToRegex = str => {
    // Main regex
    const main = str.match(/\/(.+)\/.*/)[1]
    
    // Regex options
    const options = str.match(/\/.+\/(.*)/)[1]
    
    // Compiled regex
    return new RegExp(main, options)
}

你可以这样使用它:

"abc".match(stringToRegex("/a/g"))
//=> ["a"]

2019-03-20 10:49:09

将用户输入字符串转换为正则表达式

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