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

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。

其他回答

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"]

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 '));

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, '');
var flags = inputstring.replace(/.*\/([gimy]*)$/, '$1');
var pattern = inputstring.replace(new RegExp('^/(.*?)/'+flags+'$'), '$1');
var regex = new RegExp(pattern, flags);

or

var match = inputstring.match(new RegExp('^/(.*?)/([gimy]*)$'));
// sanity check here
var regex = new RegExp(match[1], match[2]);

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);