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

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

其他回答

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RegExp对象构造函数从字符串创建正则表达式:

var re = new RegExp("a|b", "i");
// same as
var re = /a|b/i;

2009-05-17 14:26:43

感谢前面的回答，这个块作为一个通用的解决方案应用一个可配置的字符串到RegEx ..过滤文本:

var permittedChars = '^a-z0-9 _,.?!@+<>';
permittedChars = '[' + permittedChars + ']';

var flags = 'gi';
var strFilterRegEx = new RegExp(permittedChars, flags);

log.debug ('strFilterRegEx: ' + strFilterRegEx);

strVal = strVal.replace(strFilterRegEx, '');
// this replaces hard code solt:
// strVal = strVal.replace(/[^a-z0-9 _,.?!@+]/ig, '');

2015-09-21 01:45:42

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

你可以使用复选框来请求标志，然后做这样的事情:

var userInput = formInput;
var flags = '';
if(formGlobalCheckboxChecked) flags += 'g';
if(formCaseICheckboxChecked) flags += 'i';
var reg = new RegExp(userInput, flags);

2009-05-17 14:29:03

将用户输入字符串转换为正则表达式

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