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)) {
}
This question is related to
javascript
arrays
expression
look this way...
function matchInArray(stringSearch, arrayExpressions){
var position = String(arrayExpressions).search(stringSearch);
var result = (position > -1) ? true : false
return result;
}
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)
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
Consider breaking this problem up into two pieces:
filter
out the items that match
the given regular expression0
matches in itconst sampleStringData = ["frog", "pig", "tiger"];
const matches = sampleStringData.filter((animal) => /any.regex.here/.test(animal));
if (matches.length === 0) {
console.log("No matches");
}
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); });
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 */ }
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!!");
}
Source: Stackoverflow.com