Isolating the value from a Typescript regex match rather than capturing the entire

Question

Isolating the value from a Typescript regex match rather than capturing the entire

Suppose we have a URL like '/mentor/33' as an example

To manipulate this, I use regex: buildRegex('/mentor/:id');

'/mentor/:id' is transformed into '/mentor/[^/]'

const PATH_PARAM = {
    PREFIX: ':',
    REGEX_IDENTIFIER: '/:[^/]+',
    REGEX_REPLACER: '/[^/]+',
};

private buildRegex(path: string) {
        return this.ensureLeadingSlash(path).replace(
            new RegExp(PATH_PARAM.REGEX_IDENTIFIER, 'g'),
            PATH_PARAM.REGEX_REPLACER
        );
    }

How can I extract just the value 33 from '[^/]'

If I implement this function

private matchRegex(routeLink: string, routeRegex: string) {
        const match = routeLink.match(new RegExp(routeRegex, "g"));
        return match?.[0];
    }

then I end up with /mentor/33 instead of only 33. I am seeking a more generic solution.

angular typescript

Answer 1

Answer №1

To improve the matching process, encapsulate the replaced pattern within a group and reference that group instead of using [0] post matching. Depending on your specific circumstances and the dynamic nature of the content, decide whether the group should be included in the PATH_PARAM or generated dynamically whenever buildRegex is invoked.

Avoid using the global flag if you are only performing the match once.

const PATH_PARAM = {
    PREFIX: ':',
    REGEX_IDENTIFIER: '/:[^/]+',
    REGEX_REPLACER: '/[^/]+',
};
const buildRegex = (path) => {
    return path.replace(
        new RegExp(PATH_PARAM.REGEX_IDENTIFIER),
        `(?<pathinfo>${PATH_PARAM.REGEX_REPLACER})`
    );
};
const pattern = buildRegex('/mentor/:id');
const matchRegex = (routeLink, routeRegex) => {
    const match = routeLink.match(routeRegex);
    return match?.groups.pathinfo;
}
console.log(matchRegex('/mentor/33', pattern));

If the initial / is causing issues, remember that both your REGEX_IDENTIFIER and REGEX_REPLACER include a /. You can either remove the first character afterwards, alter the REGEX_IDENTIFIER and REGEX_REPLACER to exclude the slashes, or directly incorporate the group into the PATH_PARAM object instead of generating it on-the-fly.

const PATH_PARAM = {
    PREFIX: ':',
    REGEX_IDENTIFIER: '/:[^/]+',
    REGEX_REPLACER: '/(?<pathinfo>[^/]+)',
};
const buildRegex = (path) => {
    return path.replace(
        new RegExp(PATH_PARAM.REGEX_IDENTIFIER),
        PATH_PARAM.REGEX_REPLACER
    );
};
const pattern = buildRegex('/mentor/:id');
const matchRegex = (routeLink, routeRegex) => {
    const match = routeLink.match(routeRegex);
    return match?.groups.pathinfo;
}
console.log(matchRegex('/mentor/33', pattern));

Answer 2

To improve the matching process, encapsulate the replaced pattern within a group and reference that group instead of using [0] post matching. Depending on your specific circumstances and the dynamic nature of the content, decide whether the group should be included in the PATH_PARAM or generated dynamically whenever buildRegex is invoked.

Avoid using the global flag if you are only performing the match once.

const PATH_PARAM = {
    PREFIX: ':',
    REGEX_IDENTIFIER: '/:[^/]+',
    REGEX_REPLACER: '/[^/]+',
};
const buildRegex = (path) => {
    return path.replace(
        new RegExp(PATH_PARAM.REGEX_IDENTIFIER),
        `(?<pathinfo>${PATH_PARAM.REGEX_REPLACER})`
    );
};
const pattern = buildRegex('/mentor/:id');
const matchRegex = (routeLink, routeRegex) => {
    const match = routeLink.match(routeRegex);
    return match?.groups.pathinfo;
}
console.log(matchRegex('/mentor/33', pattern));

If the initial / is causing issues, remember that both your REGEX_IDENTIFIER and REGEX_REPLACER include a /. You can either remove the first character afterwards, alter the REGEX_IDENTIFIER and REGEX_REPLACER to exclude the slashes, or directly incorporate the group into the PATH_PARAM object instead of generating it on-the-fly.

const PATH_PARAM = {
    PREFIX: ':',
    REGEX_IDENTIFIER: '/:[^/]+',
    REGEX_REPLACER: '/(?<pathinfo>[^/]+)',
};
const buildRegex = (path) => {
    return path.replace(
        new RegExp(PATH_PARAM.REGEX_IDENTIFIER),
        PATH_PARAM.REGEX_REPLACER
    );
};
const pattern = buildRegex('/mentor/:id');
const matchRegex = (routeLink, routeRegex) => {
    const match = routeLink.match(routeRegex);
    return match?.groups.pathinfo;
}
console.log(matchRegex('/mentor/33', pattern));

Isolating the value from a Typescript regex match rather than capturing the entire

Answer №1

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