javascript - match string against the array of regular expressions

Question

Is there a way in JavaScript to get Boolean value for a match of the string against the array of regular expressions?

The example would be (where the \'if\' statemen

Answer 1

You can join all regular expressions into single one. This way the string is scanned only once. Even with a sligthly more complex regular expression.

var thisExpressions = [ /something/, /something_else/, /and_something_else/];
var thisString = 'else';


function matchInArray(str, expr) {
    var fullExpr = new RegExp(expr
        .map(x=>x.source) // Just if you need to provide RegExp instances instead of strings or ...
        // .map(x=>x.substring(1, x.length -2)  // ...if you need to provide strings enclosed by "/" like in original question.
        .join("|")
    )
    return str.match(fullExpr);

};


if (matchInArray(thisString, thisExpressions)) {
    console.log ("Match!!");
} 

In fact, even with this approach, if you need check the same expression set against multiple strings, this is a few suboptimal because you are building (and compiling) the same regular expression each time the function is called.

Better approach would be to use a function builder like this:

var thisExpressions = [ /something/, /something_else/, /and_something_else/];
var thisString = 'else';

function matchInArray_builder(expr) {
    var fullExpr = new RegExp(expr
        .map(x=>x.source) // Just if you need to provide RegExp instances instead of strings or ...
        // .map(x=>x.substring(1, x.length -2)  // ...if you need to provide strings enclosed by "/" like in original question.
        .join("|")
    )   

    return function (str) {
        return str.match(fullExpr);

    };
};  

var matchInArray = matchInArray_builder(thisExpressions);

if (matchInArray(thisString)) {
    console.log ("Match!!");
}