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' statement is representing what I'm trying to achieve):

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

if (matchInArray(thisString, thisExpressions)) {

} 

Answer 1

http://jsfiddle.net/9nyhh/1/

var thisExpressions = [/something/, /something_else/, /and_something_else/];
var thisExpressions2 = [/else/, /something_else/, /and_something_else/];
var thisString = 'else';

function matchInArray(string, expressions) {

    var len = expressions.length,
        i = 0;

    for (; i < len; i++) {
        if (string.match(expressions[i])) {
            return true;
        }
    }

    return false;

};

setTimeout(function() {
    console.log(matchInArray(thisString, thisExpressions));
    console.log(matchInArray(thisString, thisExpressions2));
}, 200)?

Answer 2

Using a more functional approach, you can implement the match with a one-liner using an array function:

ECMAScript 6:

const regexList = [/apple/, /pear/];
const text = "banana pear";
const isMatch = regexList.some(rx => rx.test(text));

ECMAScript 5:

var regexList = [/apple/, /pear/];
var text = "banana pear";
var isMatch = regexList.some(function(rx) { return rx.test(text); });

Answer 3

You could use .test() which returns a boolean value when is find what your looking for in another string:

var thisExpressions = [ '/something/', '/something_else/', '/and_something_else/'];
var thisString = new RegExp('\\b' + 'else' + '\\b', 'i');
var FoundIt = thisString.test(thisExpressions);  
if (FoundIt) { /* DO STUFF */ }

Answer 4

look this way...

function matchInArray(stringSearch, arrayExpressions){
    var position = String(arrayExpressions).search(stringSearch);
    var result = (position > -1) ? true : false
    return result;
}

Answer 5

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!!");
} 

Answer 6

Consider breaking this problem up into two pieces:

1. filter out the items that match the given regular expression
2. determine if that filtered list has 0 matches in it

const sampleStringData = ["frog", "pig", "tiger"];

const matches = sampleStringData.filter((animal) => /any.regex.here/.test(animal));

if (matches.length === 0) {
  console.log("No matches");
}

Answer 7

let expressions = [ '/something/', '/something_else/', '/and_something_else/'];

let str = 'else';

here will be the check for following expressions:

if( expressions.find(expression => expression.includes(str) ) ) {

}

using Array .find() method to traverse array and .include to check substring

Answer 8

Andersh's solution will not work if you have global flags.
A true return will toggle on and off on future identical tests.

regexArray.some(rx => rx.test("a"));    //true
regexArray.some(rx => rx.test("a"));    //false
regexArray.some(rx => rx.test("a"));    //true

(read why here)

This works and is also a one-liner:

const regexList = [/apple/, /pear/];
const string = "banana pear";
const isMatch = regexList.map(rx=>rx.source).includes(string);

.source returns the text of the RegExp pattern.
The arrow function returns an array of the source of every element. They will now be strings.
.includes returns if the string is in the array (if you need the index, use .indexOf)

Alternatively:

function isInsideArray(string, regexArray){
    return(regexArray.map(regex=>regex.source).includes(string)); 
}

Answer 9

If you would like to use String.match(), in case your array contains both match strings and regular expressions, you can do

let str = "The quick brown fox";
let matches = ["fox", "The.*fox", /the.*fox/i];
let strInMatches = matches.some(match => str.match(match));
console.log(strInMatches);

Answer 10

So we make a function that takes in a literal string, and the array we want to look through. it returns a new array with the matches found. We create a new regexp object inside this function and then execute a String.search on each element element in the array. If found, it pushes the string into a new array and returns.

// literal_string: a regex search, like /thisword/ig
// target_arr: the array you want to search /thisword/ig for.

function arr_grep(literal_string, target_arr) {
  var match_bin = [];
  // o_regex: a new regex object.
  var o_regex = new RegExp(literal_string);
  for (var i = 0; i < target_arr.length; i++) {
    //loop through array. regex search each element.
    var test = String(target_arr[i]).search(o_regex);
    if (test > -1) {
    // if found push the element@index into our matchbin.
    match_bin.push(target_arr[i]);
    }
  }
  return match_bin;
}

// arr_grep(/.*this_word.*/ig, someArray)