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

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

其他回答

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

我发现@Richie Bendall的解决方案非常干净。我添加了一些小的修改，因为当传递非正则字符串时，它会崩溃并抛出错误(也许这就是你想要的)。

const stringToRegex = (str) => {
const re = /\/(.+)\/([gim]?)/
const match = str.match(re);
if (match) {
    return new RegExp(match[1], match[2])
}

}

使用(gim) ?在模式中，如果匹配的[2]值无效，将忽略它。你可以省略[gim]?模式，如果您希望在正则表达式选项无效时抛出错误。

2023-01-30 23:09:55

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

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

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

将用户输入字符串转换为正则表达式

推荐文章

最新文章

标签